Polycarbonate resin composition, method for producing same and molded article of this resin composition

ABSTRACT

To provide a polycarbonate resin composition excellent in surface hardness and impact strength. 
     A polycarbonate resin composition comprising at least a polycarbonate resin (a) and a polycarbonate resin (b) having structural units different from the polycarbonate resin (a), which satisfies the requirements:
         (i) the pencil hardness of the polycarbonate resin (a) as specified by ISO15184 is higher than the pencil hardness of the polycarbonate resin (b) as specified by ISO15184;   (ii) the weight ratio of the polycarbonate resin (a) to the polycarbonate resin (b) in the polycarbonate resin is from 1:99 to 45:55;   (iii) the pencil hardness of the polycarbonate resin composition as specified by ISO15184 is higher by at least two ranks than the pencil hardness of the polycarbonate resin (b) as specified by ISO15184; and   (iv) the Charpy impact strength of the polycarbonate resin composition is higher than the Charpy impact strength of the polycarbonate resin (a).

TECHNICAL FIELD

The present invention relates to a polycarbonate resin composition and amethod for producing it. More particularly, it relates to apolycarbonate resin composition comprising at least two types ofpolycarbonate resins differing in structural units, and a method forproducing it.

BACKGROUND ART

A polycarbonate resin is excellent in the mechanical strength, theelectrical properties, the transparency and the like, and is widely usedas an engineering plastic in various fields such as electric andelectronic equipment fields and automobile fields. In recent years, insuch application fields, reduction in thickness, downsizing and weightsaving of molded article are in progress, and further improvement in theperformance of materials to be molded is required. However, aconventional polycarbonate resin made of bisphenol A as a material hasnot necessarily been sufficiently excellent in the surface hardness.Particularly in outdoor use applications, as the hardness isinsufficient, an additional treatment such as hard coating treatment hasbeen applied to the surface in many cases.

Accordingly, development of a polycarbonate resin having a high surfacehardness has been desired, and several proposals have been made.

For example, Patent Documents 1 and 2 propose a method for producing apolycarbonate or a copolycarbonate excellent in the surface hardness byusing a bisphenol different from bisphenol A as a monomer.

Patent Document 1 discloses to carry out hard coating by a hardenedcoating film comprising a compound having at least two ethylenicunsaturated bonds and urethane bonds in the same molecule.

Patent Document 2 proposes a copolycarbonate resin comprising at leasttwo types of aromatic dihydroxy compounds, as a method of increasing thehardness.

Further, Patent Document 3 proposes a method of bonding different typesof polymers on a molded specimen such as hard coating treatment, to forma multilayered structure.

Further, Patent Document 4 proposes to improve the surface hardness of ablended material of a polycarbonate resin derived from dimethylbisphenol cyclohexane and a bisphenol A type polycarbonate resin.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP-A-2005-272708

Patent Document 2: JP-A-8-183852

Patent Document 3: JP-A-2010-188719

Patent Document 4: WO2009/083933

DISCLOSURE OF INVENTION Technical Problem

However, with materials obtained by conventional methods, apolycarbonate resin composition which has high strength even though itis thin, which has excellent heat resistance and moldability, which hasa high surface hardness and which is excellent in the color, could notbe obtained.

Under these circumstances, the object of the present invention is toprovide a polycarbonate resin composition having a high hardness andhaving excellent color, impact resistance and flame retardancy, and amethod for producing it.

Further, the object of the present invention is to provide a moldedarticle of polycarbonate resin having excellent surface hardness andexcellent impact resistance, without surface hard coating or withouthaving a laminated structure comprising different polycarbonate resins.

Solution to Problem

The present inventors have conducted extensive studies to achieve theabove objects and as a result, they have found that a polycarbonateresin composition which attains the above objects can be achieved by apolycarbonate resin composition containing specific two types ofpolycarbonate resins, and accomplished the present invention.Specifically, it was found that an excellent polycarbonate resincomposition having an excellent surface hardness, having a favorablecolor and being comparable in the impact strength and moldability toconventional polycarbonate resins, can be obtained by a polycarbonateresin composition comprising a polycarbonate resin (a) having arelatively high pencil hardness and a polycarbonate resin (b), in aspecific weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b).

More specifically, it was found that by mixing the polycarbonate resin(a) and the polycarbonate resin (b) in a specific weight ratio, physicalproperties, particularly the surface hardness, of a polycarbonate resincomposition are specifically improved, and a favorable color ismaintained. For example, usually, a polycarbonate blended product and acopolymerized polycarbonate resin having the same structural units andamount, have the same properties in many cases. However, the surfacehardness of a polycarbonate resin composition of the present inventioncomprising the polycarbonate resin (a) and the polycarbonate resin (b)in a specific weight ratio is remarkably higher than the surfacehardness of a copolymerized polycarbonate resin having the samestructural units in the same weight ratio as the polycarbonate resincomposition. In addition, if the copolymerized polycarbonate resin isdesigned to have the surface hardness at the same level as thepolycarbonate resin composition of the present invention, the color isdefinitely deteriorated.

The present invention provides the following <1> to <30>.

That is, the present invention provides, first, the followingpolycarbonate resin composition.

<1> A polycarbonate resin composition comprising at least apolycarbonate resin (a) and a polycarbonate resin (b) having structuralunits different from the polycarbonate resin (a), which satisfies thefollowing requirements:

(i) the pencil hardness of the polycarbonate resin (a) as specified byISO 15184 is higher than the pencil hardness of the polycarbonate resin(b) as specified by ISO 15184;

(ii) the weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b) is from 1:99 to 45:55;

(iii) the pencil hardness of the polycarbonate resin composition asspecified by ISO 15184 is higher by at least two ranks than the pencilhardness of the polycarbonate resin (b) as specified by ISO 15184; and

(iv) the Charpy impact strength of the polycarbonate resin compositionis higher than the Charpy impact strength of the polycarbonate resin(a).

<2> A polycarbonate resin composition comprising at least apolycarbonate resin (a) and a polycarbonate resin (b) having structuralunits different from the polycarbonate resin (a), which satisfies thefollowing requirements:

(i) the pencil hardness of the polycarbonate resin (a) as specified byISO 15184 is higher than the pencil hardness of the polycarbonate resin(b) as specified by ISO 15184;

(ii) the weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b) is from 1:99 to 45:55;

(iii) the ratio of the viscosity average molecular weight Mv(a) of thepolycarbonate resin (a) to the viscosity average molecular weight Mv(b)of the polycarbonate resin (b), Mv(a)/Mv(b), is at least 0.02 and atmost 1.5.

<3> The polycarbonate resin according to the above <2>, wherein theabove Mv(a) is at most 20,000.

<4> A polycarbonate resin composition comprising at least apolycarbonate resin (a) and a polycarbonate resin (b) having structuralunits different from the polycarbonate resin (a), which satisfies thefollowing requirements:

(i) the pencil hardness of the polycarbonate resin (a) as specified byISO 15184 is higher than the pencil hardness of the polycarbonate resin(b) as specified by ISO 15184;

(ii) the weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b) is from 1:99 to 45:55;

(iii) the melt viscosity of the polycarbonate resin (b) at a temperatureof 280° C. at a shear rate of 122 sec⁻¹ is higher than the meltviscosity of the polycarbonate resin (a) at a temperature of 280° C. ata shear rate of 122 sec⁻¹.

<5>. The polycarbonate resin composition according to any one of theabove <1> to <4>, wherein the pencil hardness of the polycarbonate resin(a) as specified by ISO 15184 is at least F.

<6> The polycarbonate resin composition according to any one of theabove <1> to <5>, wherein the pencil hardness of the polycarbonate resincomposition as specified by ISO 15184 is at least HB.

<7> The polycarbonate resin composition according to any one of theabove <1> to <6>, wherein the polycarbonate resin (a) is a polycarbonateresin having at least structural units derived from a compoundrepresented by the following formula (1):

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.<8> The polycarbonate resin composition according to the above <7>,wherein the polycarbonate resin (a) is a polycarbonate resin having atleast structural units (a) derived from at least one compound selectedfrom the group consisting of the following formulae (1a) to (1c):

<9> The polycarbonate resin composition according to any one of theabove <1> to <8>, wherein the polycarbonate resin (b) is a polycarbonateresin having mainly structural units (b) derived from a compoundrepresented by the following formula (2):

<10> The polycarbonate resin composition according to any one of theabove <1> to <9>, which has a yellowness index (YI) of at most 4.0.<11> The polycarbonate resin composition according to any one of theabove <1> to <10>, which further contains a flame retardant.<12> A method for producing the polycarbonate resin composition asdefined in any one of the above <1> to <11>, which comprisesmelt-kneading the polycarbonate resin (a) and the polycarbonate resin(b).<13> A method for producing the polycarbonate resin composition asdefined in any one of the above <1> to <11>, which comprisesdry-blending the polycarbonate resin (a) and the polycarbonate resin(b).<14> An injection-molded article, which is obtained by injection-moldingthe polycarbonate resin composition as defined in any one of the above<1> to <11>.<15> An extruded article, which is obtained by extruding thepolycarbonate resin composition as defined in any one of the above <1>to <11>.<16> The extruded article according to the above <15>, which is a sheetor a film.<17> A molded article of polycarbonate resin having structural units (a)derived from a compound represented by the following formula (1) andstructural units (b) different from the structural units (a), whereinthe ratio of the content [S] of the structural units (a) on the surfaceof the molded article of polycarbonate resin to the content [T] in theentire molded article of polycarbonate resin ([S]/[T]) is higher than1.00 and at most 2.00:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.<18> The molded article of polycarbonate resin according to the above<17>, which is an injection-molded article.<19 The molded article of polycarbonate resin according to the above<17> or <18>, wherein the ratio of the content [S] of the structuralunits (a) on the surface of the molded article of polycarbonate resin tothe content [T] in the entire molded article of polycarbonate resin([S]/[T]) is at least 1.01 and at most 1.50.<20> The molded article of polycarbonate resin according to any one ofthe above <17> to <19>, wherein the pencil hardness on the surface ofthe molded article of polycarbonate resin as specified by ISO 15184 isat least HB.<21> The molded article of polycarbonate resin according to any one ofthe above <17> to <20>, wherein the structural units (a) are structuralunits derived from at least one compound selected from the groupconsisting of the following formulae (1a) to (1c):

<22> The molded article of polycarbonate resin according to any one ofthe above <17> to <21>, wherein the structural units (b) are mainlystructural units derived from a compound of the following formula (2):

<23> The molded article of polycarbonate resin according to any one ofthe above <17> to <22>, which comprises at least a polycarbonate resin(a) having structural units (a) derived from a compound represented bythe formula (1) and a polycarbonate resin (b) having structural units(b) different from the structural units (a) and having a structuredifferent from the polycarbonate resin (a).<24> The molded article of polycarbonate resin according to the above<23>, wherein the pencil hardness of the polycarbonate resin (a) asspecified by ISO 15184 is higher than the pencil hardness of thepolycarbonate resin (b) as specified by ISO 15184.<25> The molded article of polycarbonate resin according to the above<23> or <24>, wherein the pencil hardness of the polycarbonate resin (a)as specified by ISO 15184 is at least F.<26> The molded article of polycarbonate resin according to any one ofthe above <23> to <25>, wherein the viscosity average molecular weightof the polycarbonate resin (a) is higher than the viscosity averagemolecular weight of the polycarbonate resin (b).<27> A method for producing the molded article of polycarbonate resin asdefined in any one of the above <23> to <26>, comprising at least apolycarbonate resin (a) having structural units (a) derived from acompound represented by the following formula (1) and a polycarbonateresin (b) having structural units (b) different from the structuralunits (a), which comprises melt-kneading or dry-blending thepolycarbonate resin (a) and the polycarbonate resin (b), followed bymolding, wherein the viscosity average molecular weight of thepolycarbonate resin (a) is higher than the viscosity average molecularweight of the polycarbonate resin (b):

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.<28> The method for producing the molded article of polycarbonate resinaccording to the above <27>, wherein the structural units (a) arestructural units derived from at least one compound selected from thegroup consisting of the following formulae (1a) to (1c):

<29> The method for producing the molded article of polycarbonate resinaccording to the above <27> or <28>, wherein the structural units (b)are mainly structural units derived from a compound of the followingformula (2):

<30> The method for producing the molded article of polycarbonate resinaccording to any one of the above <27> to <29>, wherein the molding isinjection molding.

Advantageous Effects of Invention

According to the present invention, it is possible to obtain apolycarbonate resin composition having a remarkably improved surfacehardness and having a favorable color, and having the impact resistanceand the moldability well balanced. That is, by a polycarbonate resincomposition comprising a polycarbonate resin (b) and a polycarbonateresin (a) having a relatively high pencil hardness in a specific weightratio, it is possible to increase the surface hardness, to maintain afavorable color and to make the impact resistance and the moldability bewell balanced, without impairing the physical properties of thepolycarbonate resin (b). For example, in a case where a bisphenol A typepolycarbonate is used as the polycarbonate resin (b), the surfacehardness which is a disadvantage of the bisphenol A type polycarbonatecan be improved while minimizing a decrease in the impact resistance,the transparency, the color and the like which are characteristics ofthe bisphenol A type polycarbonate.

Further, according to the present invention, a polycarbonate resinmolded article having an excellent surface hardness and having goodflame retardancy can be provided.

DESCRIPTION OF EMBODIMENTS

The present invention relates to, first, a polycarbonate resincomposition comprising at least a polycarbonate resin (a) and apolycarbonate resin (b) having structural units different from thepolycarbonate resin (a), which satisfies the following requirements (i)to (iv).

In the present invention, “having different structural units” means [I]“having different types of structural units” in a case where each of thepolycarbonate resin (a) and the polycarbonate resin (b) is ahomopolymer, and means [II] (A) having different types of structuralunits or (B) having the same type of structural units and having adifferent compositional ratio of the structural units in a case where atleast one of the polycarbonate resin (a) and the polycarbonate resin (b)is a copolymer.

That is, a specific example of the above [I] is a case where thepolycarbonate resin (a) is a homopolymer comprising structural units (a)and the polycarbonate resin (b) is a homopolymer comprising structuralunits (b).

A specific example of [II] (A) is a case where the polycarbonate resin(a) is a copolymer comprising structural units (a) and structural units(c), and the polycarbonate resin (b) is a copolymer comprisingstructural units (b) and structural units (c).

A specific example of the above [II] (B) is a case where each of thepolycarbonate resin (a) and the polycarbonate resin (b) comprisesstructural units (a) and structural units (b), however, thepolycarbonate resin (a) and the polycarbonate resin (b) are different inthe ratio of the structural units (a) to the structural units (b).

First, the requirement (i) is that the pencil hardness of thepolycarbonate resin (a) constituting the polycarbonate resin compositionof the present invention as specified by ISO 15184 is higher than thepencil hardness of the polycarbonate resin (b) as specified by ISO15184. Here, the pencil hardness of the polycarbonate resin or thepolycarbonate resin composition specified here is the pencil hardnessmeasured in the form of an injection-molded article, as described in theevaluation method “(1) pencil hardness of molded article” in Examples indetail. Hereinafter, in this specification, “the pencil hardness” meansthis pencil hardness of an injection-molded article, unless otherwisespecified.

If the pencil hardness of the polycarbonate resin (a) is equal to orlower than the pencil hardness of the polycarbonate resin (b), thepencil hardness of the polycarbonate resin composition may be low, andthe surface of a molded article is likely to be scarred.

A favorable pencil hardness of the polycarbonate resin (a) is at least Fby the pencil hardness as specified by ISO 15184. If the pencil hardnessof the polycarbonate resin (a) is less than F, the pencil hardness ofthe polycarbonate resin composition may not sufficiently be improved insome cases.

Then, the requirement (ii) is that the weight ratio of the polycarbonateresin (a) to the polycarbonate resin (b) in the polycarbonate resincomposition of the present invention is within a range of from 1:99 to45:55. It is preferably from 3:97 to 45:55, more preferably from 5:95 to40:60, further preferably from 10:90 to 30:70. If the proportion of thepolycarbonate resin (a) is too high, the color of an obtainablepolycarbonate resin composition tends to be impaired, and no sufficientimpact resistance will be obtained, and if the proportion of thepolycarbonate resin (a) is too low, the pencil hardness may beinsufficient.

Further, the requirement (iii) is that the pencil hardness of thepolycarbonate resin composition of the present invention as specified byISO 15184 is higher by at least two ranks than the pencil hardness ofthe polycarbonate resin (b) as specified by ISO 15184, and it ispreferably higher by at least three ranks.

The pencil hardness ranks are, from lower ranks, 2B, B, HB, F, H, 2H, 3Hand 4H, and the pencil hardness of the polycarbonate resin compositionbeing higher by at least two ranks than the pencil hardness of thepolycarbonate resin (b) means, for example, a pencil hardness of atleast HB when the pencil hardness of the polycarbonate resin (b) is 2B,a pencil hardness of at least F when the pencil hardness of thepolycarbonate resin (b) is B, and a pencil hardness of at least H whenthe pencil hardness of the polycarbonate resin (b) is HB.

Further, as the requirement (iv), it is required that the Charpy impactstrength of the polycarbonate resin composition comprising thepolycarbonate resin (a) and the polycarbonate resin (b) is higher thanthe Charpy impact strength of the polycarbonate resin (a).

The Charpy impact strength of the polycarbonate resin composition isproperly determined depending upon the shape, the purpose of use and thelike of a final product, and is usually at least 8 kJ/m², preferably atleast 10 kJ/m². If the Charpy impact strength is less than 8 kJ/m², themolded article of polycarbonate resin tends to be easily broken. TheCharpy impact strength of the molded article of polycarbonate resin canbe determined by a measurement method based on JIS K7111. The specificmeasurement method will be described in detail in Examples.

The polycarbonate resin (a) and the polycarbonate resin (b) havingstructural units different from the polycarbonate resin (a) are notparticularly limited so long as the above requirements (i) to (iii) aresatisfied.

As described above, the polycarbonate resin composition of the presentinvention comprises a polycarbonate resin (b) having a relatively lowpencil hardness and a polycarbonate resin (a) having a relatively highpencil hardness in a specific weight ratio, wherein the pencil hardnessof the polycarbonate resin composition is higher by at least two ranksthan the polycarbonate resin (b), and the Charpy impact strength of thepolycarbonate resin composition is higher than the polycarbonate resin(a).

By such a constitution, it is possible to obtain a polycarbonate resincomposition which has a remarkably improved surface hardness and has afavorable color, and which has the impact strength and the moldabilitywell balanced.

As described above, the polycarbonate resin composition of the presentinvention comprises a polycarbonate resin (b) having a relatively lowpencil hardness and a polycarbonate resin (a) having a relatively highpencil hardness in a specific weight ratio, wherein the ratio of theviscosity average molecular weight Mv(a) of the polycarbonate resin (a)to the viscosity average molecular weight Mv(b) of the polycarbonateresin (b), Mv(a)/Mv(b), is within a specific range. Specifically, theratio of the viscosity average molecular weight Mv(a) of thepolycarbonate resin (a) to the viscosity average molecular weight Mv(b)of the polycarbonate resin (b), Mv(a)/Mv(b), is preferably at least 0.02and at most 2.0, more preferably at least 0.3 and at most 1.5, furtherpreferably at least 0.4 and at most 1.2. If Mv(a)/Mv(b) is less than0.02, the surface hardness of the polycarbonate resin composition tendsto be low. If Mv(a)/Mv(b) is low, the impact resistance may bedecreased. Further, if Mv(a)/Mv(b) is high, the effect of improving thesurface hardness tends to be small, and the surface hardness of thepolycarbonate resin composition may be low. Further, the melt viscositytends to be very high, whereby the fluidity will be deteriorated and themoldability are poor in some cases.

By the above constitution, it is possible to obtain a polycarbonateresin composition which has a high and favorable surface hardness, andis also excellent in the color and the impact resistance.

As described above, the polycarbonate resin composition of the presentinvention is a polycarbonate resin composition comprising apolycarbonate resin (b) having a relatively low pencil hardness and ahigh melt viscosity and a polycarbonate resin (a) having a relativelyhigh pencil hardness and a low melt viscosity in a specific weightratio. Specifically, it is required that the melt viscosity of thepolycarbonate resin (b) at a temperature of 280° C. at a shear rate of122 sec⁻¹ (hereinafter sometimes referred to simply as “melt viscosityof the polycarbonate resin (b)”) is higher than the melt viscosity ofthe polycarbonate resin (a) at a temperature of 280° C. at a shear rateof 122 sec⁻¹ (hereinafter sometimes referred to simply as “meltviscosity of the polycarbonate resin (a)”).

If this requirement is not satisfied, the effect of improving thesurface hardness tends to be small, and the color may be deteriorated,such being unfavorable. The melt viscosity can be measured by acapillary rheometer “Capirograph 1C” (manufactured by TOYO SEIKISEISAKU-SHO, LTD.) described in Examples in detail.

By the above constitution, it is possible to obtain a polycarbonateresin composition which has high strength even though it is thin, whichhas a high surface hardness, which has high and favorable moldability,and which is also excellent in the color and the impact resistance.

Usually, a composition of polycarbonate resins and a copolymerizedpolycarbonate resin having the same structural units and amounts, havethe same physical properties in many cases. However, although the reasonin detail is not clearly understood at present, the surface hardness ofthe polycarbonate resin composition comprising the polycarbonate resin(a) and the polycarbonate resin (b) of the present invention isremarkably high as compared with the surface hardness of a copolymerizedpolycarbonate having the same structural units in the same weight ratioas the polycarbonate resin composition.

The polycarbonate resin composition of the present invention preferablysatisfies the following.

The pencil hardness of the polycarbonate resin composition of thepresent invention as specified by ISO 15184 is usually at least HB,preferably at least F, more preferably at least H. If the pencilhardness is low, the surface hardness tends to be low, and when it ismolded into a molded article, it is easily scarred in some cases.

The yellowness index (YI) of the polycarbonate resin composition of thepresent invention is usually at most 4.0, preferably at most 3.5,further preferably at most 3.0, particularly preferably at most 2.5.Usually it is at most 3.0, preferably at most 2.8, further preferably atmost 2.5. If YI is too high, the color tends to be deteriorated, thedesign as a molded article tends to be poor, and particularly in amolded article which is required to be colored, the brightness may beinsufficient, and the color may be smoky.

The melt viscosity of the polycarbonate resin composition of the presentinvention is preferably at most 30,000 poise, more preferably at most25,000 poise, further preferably at most 11,000 poise, particularlypreferably at most 9,000 poise, at a temperature of 280° C. at a shearrate of 122 sec⁻¹. If the melt viscosity is at least 30,000 poise, thefluidity may remarkably be decreased, and the moldability may beimpaired. The melt viscosity is a value measured by a capillaryrheometer “Capirograph 1C” (manufactured by TOYO SEIKI SEISAKU-SHO,LTD.).

The melt viscosity of the polycarbonate resin (a) is usually within arange of from 500 to 30,000 poise, preferably from 1,000 to 25,000poise, further preferably from 1,500 to 20,000 poise.

If the melt viscosity of the polycarbonate resin (a) is too high, theeffect of improving the surface hardness of the obtainable polycarbonateresin composition may be small, and the color of the molded article maybe deteriorated, such being unfavorable.

Further, if the melt viscosity of the polycarbonate resin (a) is toolow, the glass transition temperature (Tg) of the obtainablepolycarbonate resin composition tends to be low, the heat resistance maybe impaired, and the impact resistance of the obtainable polycarbonateresin composition may be low, such being unfavorable.

The melt viscosity of the polycarbonate resin (b) is usually within arange of from 1,000 to 40,000 poise, preferably from 3,000 to 30,000poise, further preferably from 5,000 to 25,000 poise.

If the melt viscosity of the polycarbonate resin (b) is too high, theeffect of improving the surface hardness of the obtainable polycarbonateresin composition may be small, and YI of the molded article may behigh, such being unfavorable.

If the melt viscosity of the polycarbonate resin (b) is too low, theglass transition temperature (Tg) of the obtainable polycarbonate resincomposition tends to be low, the heat resistance may be impaired, andthe impact resistance of the obtainable polycarbonate resin compositionmay be low, such being unfavorable.

The viscosity average molecular weight of the polycarbonate resin (a) isusually within a range of from 1,000 to 100,000, preferably from 3,000to 50,000, more preferably from 5,000 to 30,000, further preferably from6,000 to 20,000, most preferably from 6,000 to 19,000. If the viscosityaverage molecular weight is too high, the melt viscosity of thepolycarbonate resin composition tends to be high, and the effect ofimproving the surface hardness may be small, such being unfavorable.Further, if the viscosity average molecular weight is too low, theeffect of improving the surface hardness of the polycarbonate resincomposition tends to be small, and the impact resistance, the strengthor the like may be low in some cases, such being unfavorable.

The viscosity average molecular weight of the polycarbonate resin (b) isusually within a range of from 1,000 to 100,000, preferably from 5,000to 50,000, more preferably from 10,000 to 40,000, further preferablyfrom 20,000 to 30,000. If the viscosity average molecular weight is toohigh, the melt viscosity of the polycarbonate resin composition tends tobe high, whereby the fluidity may be decreased, such being unfavorable.Further, if the viscosity average molecular weight is too low, theeffect of improving the surface hardness of the resin composition tendsto be small, and the impact resistance, the strength or the like may below in some cases, such being unfavorable.

Further, the present invention relates to a molded article ofpolycarbonate resin having structural units (a) derived from a compoundrepresented by the following formula (1) and structural units (b)different from the structural units (a), wherein the ratio of thecontent [S] of the structural units (a) on the surface of the moldedarticle of polycarbonate resin to the content [T] of the structuralunits (a) in the entire molded article of polycarbonate resin ([S]/[T])is higher than 1.00 and at most 2.00:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.

The present invention is characterized in that in the molded article ofpolycarbonate resin having the above two types of structural units, theratio of the content [S] of the structural units (a) on the surface ofthe molded article of polycarbonate resin to the content [T] of thestructural units (a) in the entire molded article of polycarbonate resin([S]/[T]) is higher than 1.00 and at most 2.00, preferably at least 1.01and at most 1.50, further preferably at least 1.10 and at most 1.20.

That is, in the molded article of polycarbonate resin of the presentinvention, the content of the structural units (a) on the surface of themolded article of polycarbonate resin is higher than the content of thestructural units (a) in the entire molded article of polycarbonateresin.

As mentioned above, a molded article of polycarbonate resin containing alarger amount of the structural units (a) on the surface of the moldedarticle of polycarbonate resin, has a remarkably improved surfacehardness and has a favorable color, and has improved impact resistance.

Particularly when the above [S]/[T] is at least 1.01 and at most 1.50, amolded article of polycarbonate resin which is more excellent in thesurface hardness and the impact resistance will be obtained.

The content [S] of the structural units (a) on the surface of the moldedarticle of polycarbonate resin and the content [T] of the structuralunits (a) in the entire molded article of polycarbonate resin can beobtained by an NMR method. More specifically, the molar composition ofeach structural units can be obtained by the integrated intensity ratioof signals characteristics of a dihydroxy compound observed by ¹H-NMRmeasurement of a deuterochloroform solution of the molded article ofpolycarbonate resin using a nuclear magnetic resonance apparatus (NMRapparatus). The weight ratio of each structural units is determined fromthe obtained molar composition and the formula weight of each structuralunits.

Specific methods of obtaining the content [S] of the structural units(a) on the surface of the molded article of polycarbonate resin and thecontent [T] of the structural units (a) in the entire molded article ofpolycarbonate resin are as follows.

[I] Content [S] of Structural Units (a) on the Surface of Molded Articleof Polycarbonate Resin

The entire molded article of polycarbonate resin is immersed inmethylene chloride at room temperature (25° C.). 5 seconds afterinitiation of immersion, the molded article of polycarbonate resin istaken out from methylene chloride to obtain a methylene chloridesolution. Methylene chloride is removed from the methylene chloridesolution to obtain a residue. The residue is dissolved indeuterochloroform, and the obtained solution is subjected to measurementby ¹H-NMR method.

From the signal intensity of the structural units (a) and the signalintensities of other structural units in the obtained ¹H-NMR spectrum,the proportion of the structural units (a) to all the structural unitsobtained in total is calculated and regarded as the content [S] (wt %)of the structural units (a) on the surface of the molded article ofpolycarbonate resin.

[II] Content [T] of Structural Units (a) in the Entire Molded Article ofPolycarbonate Resin

The entire molded article of polycarbonate resin is immersed inmethylene chloride at room temperature (25° C.) and completely dissolvedto obtain a methylene chloride solution. About 50 g of the methylenechloride solution is taken, and methylene chloride is removed from themethylene chloride solution to obtain a residue. The residue isdissolved in deuterochloroform, and the obtained solution is subjectedto measurement by ¹H-NMR method.

From the signal intensity of the structural units (a) and the signalintensities of other structural units in the obtained ¹H-NMR spectrum,the proportion of the structural units (a) to all the structural unitsobtained in total is calculated and regarded as the content [T] (wt %)of the structural units (a) in the entire molded article.

The molded article of polycarbonate resin of the present invention ispreferably an injection-molded article.

An injection-molded article has advantages in that molded articleshaving a complicated shape can be molded in a high cycle rate.

The pencil hardness on the surface of the molded article ofpolycarbonate resin of the present invention as specified by ISO 15184is usually at least HB, preferably at least F, further preferably atleast H. If the pencil hardness on the surface of the molded article ofpolycarbonate resin is low, the molded article is likely to be scarredin some cases. The pencil hardness ranks are, from lower ranks, 2B, B,HB, F, H, 2H, 3H and 4H.

The conditions for molding the molded article of polycarbonate resinwhen the surface pencil hardness is evaluated are not particularlylimited, and an optional forming method may be employed.

Now, the polycarbonate resin (a) and a polycarbonate resin suitable asthe polycarbonate resin (b) having structural units different from thepolycarbonate resin (a), constituting the polycarbonate resincomposition of the present invention, will be described.

<Polycarbonate Resin (a)>

As the polycarbonate resin (a), first, a polycarbonate resin having atleast structural units (a) derived from a compound represented by thefollowing formula (1) may be mentioned as a suitable example:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.

In the above formula (1), as each of R¹ and R², the substituted ornon-substituted C₁₋₂₀ alkyl group may, for example, be a methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl,sec-pentyl, n-hexyl, n-heptyl or n-octyl group, and the substituted ornon-substituted aryl group may, for example, be a phenyl, benzyl, tolyl,4-methylphenyl or naphthyl group.

As each of R³ and R⁴, the substituted or non-substituted C₁₋₂₀ alkylgroup may, for example, be a methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, n-hexyl,n-heptyl or n-octyl group, and the substituted or non-substituted arylgroup may, for example, be a phenyl, benzyl, tolyl, 4-methylphenyl ornaphthyl group.

Among them, each of R¹ and R² is preferably a methyl, ethyl, n-propyl or4-methylphenyl group, particularly preferably a methyl group. Each of R³and R⁴ is preferably a hydrogen atom, a methyl, ethyl, n-propyl or4-methylphenyl group, particularly preferably a hydrogen atom. Here, thebonding positions of R¹, R², R³ and R⁴ in the formula (1) are optionalpositions selected from 2-, 3-, 5- and 6-positions relative to X on thephenyl rings, and are preferably 3-position or 5-position.

Further, in the formula (1), in a case where X is a substituted ornon-substituted alkylidene group, it is represented by the followingstructural formulae. As X, the oxidized or not-oxidized sulfur atom may,for example, be —S— or —SO₂—.

wherein each of R⁵ and R⁶ which are independent of each other, is ahydrogen atom, a substituted or non-substituted C₁₋₂₀ alkyl group or asubstituted or non-substituted aryl group, and Z is a substituted ornon-substituted C₄₋₂₀ alkylene group or a polymethylene group, and n isan integer of from 1 to 10.

As each of R⁵ and R⁶, the substituted or non-substituted C₁₋₂₀ alkylgroup may, for example, be a methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, n-hexyl,n-heptyl or n-octyl group, and the substituted or non-substituted arylgroup may, for example, be a phenyl, benzyl, tolyl, 4-methylphenyl ornaphthyl group.

Among them, each of R⁵ and R⁶ is preferably a methyl, ethyl, n-propyl or4-methylphenyl group, particularly preferably a methyl group. It isparticularly preferred that both of R⁵ and R⁶ are methyl groups and n is1, that is, X in the formula (1) is an isopropylidene group.

Z in the formula (1) is bonded to the carbon atom bonded to the twophenyl groups, and forms a substituted or non-substituted bivalentcarbon ring. The bivalent carbon ring may, for example, be a (preferablyC₄₋₁₂) cycloalkylidene group such as a cyclopentylidene,cyclohexylidene, cycloheptylidene, cyclododecylidene or adamantylidenegroup, and the substituted carbon ring may, for example, be such a grouphaving a methyl substituent or an ethyl substituent. Among them,preferred is a cyclohexylidene group, a methyl-substitutedcyclohexylidene group or a cyclododecylidene group.

Among polycarbonate resins (a) having at least structural units derivedfrom a compound represented by the above formula (1), a polycarbonateresin having structural units (a) derived from at least one compoundselected from the group consisting of the following formulae (1a) to(1i) is suitably used.

Among the above compounds, a polycarbonate resin having structural units(a) derived from at least one compound selected from the groupconsisting of the above formulae (1a) to (1c) is more suitably used.

The polycarbonate resin (a) may contain structural units other than thestructural units derived from the compound represented by the aboveformula (1), within a range not to impair the performance.

The structural units other than the structural units (a) are notparticularly limited and may, for example, be specifically structuralunits derived from an alicyclic dihydroxy compound such as2,2-bis(4-hydroxyphenyl)propane (hereinafter sometimes referred to as“bisphenol A”) or absolute sugar alcohol, or a cyclic ether compoundsuch as spiroglycol.

From the viewpoint of easiness of production of the molded article ofpolycarbonate resin of the present invention, the content of thestructural units (a) in the polycarbonate resin (a) is preferably atleast 50 wt %, more preferably at least 75 wt %, particularly preferablyat least 95 wt % (including 100 wt %) based on 100 wt % of all thestructural units in the polycarbonate resin (a).

The content of the structural units in the polycarbonate resin (a) canbe obtained by the NMR method described in the above molded article ofpolycarbonate resin.

<Polycarbonate Resin (b)>

Then, as the polycarbonate resin (b), a polycarbonate resin havingstructural units (b) derived from at least one compound selected fromthe group consisting of the following formulae (2) to (13) is suitablyused, and a bisphenol A type polycarbonate resin having mainlystructural units derived from bisphenol A represented by the followingformula (2) is more suitably used. Here, “having mainly structural unitsderived from bisphenol A” means that among the structural unitsconstituting the polycarbonate resin (b), at least 50 wt %, preferablyat least 80 wt %, more preferably at least 90 wt % are structural unitsderived from bisphenol A.

Here, the polycarbonate resin (b) contains the structural units (b)which are structural units other than the structural units (a) and mayhave structural units other than the structural units (b). Accordingly,the polycarbonate resin (b) may have structural units (a) (that is, thepolycarbonate resin (b) is a copolymer having the structural units (a)and the structural units (b)).

On the other hand, if the polycarbonate resin (b) contains a largeamount of the structural units (a), the color may be deteriorated, orthe impact strength may be decreased, and accordingly, the proportion ofthe structural units (a) contained in the polycarbonate resin (b) ispreferably less than 50 wt %, more preferably less than 25 wt %, andpreferably less than 5 wt % (including 0 wt %), based on 100 wt % of allthe structural units in the polycarbonate resin (b).

The content of the structural units in the polycarbonate resin (b) canbe obtained by the NMR method. Specifically, the molar composition ofeach structural units can be obtained from the integrated intensityratio of signals characteristics of a dihydroxy compound used when thepolycarbonate resin (b) is prepared, observed by ¹H-NMR measurement of adeuterochloroform solution of the polycarbonate resin (b) using anuclear magnetic resonance apparatus (NMR apparatus). The weight ratioof each structural units is determined from the obtained molarcomposition and the formula weight of each structural units.

<Content of Structural Units in Molded Article of Polycarbonate Resin>

The content (average content) of the structural units (a) in the moldedarticle of polycarbonate resin of the present invention is notparticularly limited, and is usually less than 50 wt %, preferably atmost 20 wt %, based on 100 wt % of all the structural units (the totalof the structural units (a), the structural units (b) and otherstructural units) in the polycarbonate resin.

The content of the structural units in the molded article ofpolycarbonate resin can be obtained by the NMR method.

The molded article of polycarbonate resin of the present invention ispreferably a molded article of polycarbonate resin comprising at least apolycarbonate resin (a) having structural units (a) derived from acompound represented by the above formula (1) and a polycarbonate resin(b) having structural units (b) different from the structural units (a)and having a structure different from the polycarbonate resin (a), inview of easy production.

The polycarbonate resin (b) is a polycarbonate resin having structuralunits (b) different from the structural units (a) and having a structuredifferent from the polycarbonate resin (a). That is, the polycarbonateresin (b) has “a structure different” from the polycarbonate resin (a)not only when the polycarbonate resin (a) is a homopolymer comprisingstructural units (a) and the polycarbonate resin (b) is a homopolymercomprising structural units (b), but also when the polycarbonate resin(b) is a copolymer having structural units (a) as structural units otherthan the structural units (b).

In a case where the molded article of polycarbonate resin of the presentinvention comprises the above polycarbonate resin (a) and polycarbonateresin (b), the pencil hardness of the polycarbonate resin (a) asspecified by ISO 15184 is preferably higher than the pencil hardness ofthe polycarbonate resin (b) as specified by ISO 15184.

If the pencil hardness of the polycarbonate resin (a) is equal to orlower than the pencil hardness of the polycarbonate resin (b), thepencil hardness of the polycarbonate resin molded article may be low,and the surface of the molded article of polycarbonate resin is likelyto be scarred.

A suitable pencil hardness of the polycarbonate resin (a) is at least Fby the pencil hardness as specified by ISO 15184. If the pencil hardnessof the polycarbonate resin (a) is less than F, the pencil hardness ofthe molded article of polycarbonate resin may not sufficiently beimproved in some cases.

With respect to the pencil hardnesses of the polycarbonate resin (a) andthe polycarbonate resin (b), the surface hardnesses of a molded articleof polycarbonate resin obtainable by a method described in the pencilhardness on the surface of the molded article of polycarbonate resindescribed in Examples are regarded as pencil hardnesses of thepolycarbonate resin (a) and the polycarbonate resin (a).

Further, in a case where the molded article of polycarbonate resin ofthe present invention comprises the above polycarbonate resin (a) andpolycarbonate resin (b), the viscosity average molecular weight of thepolycarbonate resin (a) is preferably higher than the viscosity averagemolecular weight of the polycarbonate resin (b). It is estimated that amolded article of polycarbonate resin having a different content of thestructural units between on the surface of the molded article ofpolycarbonate resin and in the entire molded article of polycarbonateresin can be obtained by such a difference in the viscosity averagemolecular weight.

<Method for Producing Polycarbonate Resin>

Now, the method for producing the polycarbonate resin (a) and thepolycarbonate resin (b) of the present invention will be described below(hereinafter “the polycarbonate resin (a) and the polycarbonate resin(b)” will generally be referred to as “polycarbonate resin” in somecases.)

The polycarbonate resin of the present invention is obtainable bypolymerization by using a dihydroxy compound and a carbonyl compound.Specifically, there are an interfacial polycondensation method(hereinafter sometimes referred to as “interfacial method”) forproducing a polycarbonate resin by reacting a dihydroxy compound andcarbonyl chloride (hereinafter sometimes referred to as “CDC” or“phosgene” at an interface between an organic phase and an aqueous phasewhich are not miscible optionally, and a melt polycondensation method(hereinafter sometimes referred to as “melt method”) for producing apolycarbonate resin by subjecting a dihydroxy compound and a carbonylcompound to an ester exchange reaction in a molten state in the presenceof an ester exchange reaction catalyst.

Now, each of the interfacial method and the melt method may specificallybe described.

<Interfacial Method>

The polycarbonate resin of the present invention by the interfacialmethod is usually obtained in such a manner that an alkaline aqueoussolution of a dihydroxy compound is prepared (raw material preparationstep), the interfacial polycondensation reaction of the dihydroxycompound and phosgene (COCl₂) is carried out in an organic solvent inthe presence of, for example, an amine compound, as a polycondensationcatalyst, followed by steps of neutralization, washing with water anddrying to obtain the polycarbonate resin. Specifically, thepolycarbonate resin production process by the interfacial methodcomprises at least a raw material preparation step of preparing rawmaterials such as a monomer component, an oligomerization step to carryout an oligomerization reaction, a polycondensation step of carrying outa polycondensation reaction using the oligomer, a washing step ofwashing the reaction liquid after the polycondensation reaction byalkali washing, acid washing and water washing, a polycarbonate resinisolation step of pre-concentrating the washed reaction liquid andisolating the polycarbonate resin after granulation, and a drying stepof drying isolated polycarbonate resin particles.

In the interfacial method, usually an organic solvent is used.

Now, the respective steps will be described.

(Raw Material Preparation Step)

In the raw material preparation step, in a raw material preparationtank, a raw material of e.g. an alkaline aqueous solution of a dihydroxycompound containing a dihydroxy compound, an aqueous solution of a metalcompound such as sodium hydroxide (NaOH) or magnesium hydroxide(Mg(OH)₂), demineralized water (DMW) and further as the case requires, areducing agent such as hydrosulfite (HS) is prepared.

(Dihydroxy Compound)

As the dihydroxy compound which is a raw material of the polycarbonateresin of the present invention, specifically, dihydroxy compoundsrepresented by the formulae (1a) to (1i) represented by the aboveformula (1) and the formulae (2) to (13) may, for example, be mentioned.

(Metal Compound)

The metal compound is usually preferably a hydroxide, such as sodiumhydroxide, lithium hydroxide, potassium hydroxide, magnesium hydroxideor calcium hydroxide. Among them, sodium hydroxide is particularlypreferred.

The proportion of the metal compound to the dihydroxy compound isusually from 1.0 to 1.5 (equivalent ratio), preferably from 1.02 to 1.04(equivalent ratio). If the proportion of the metal compound isexcessively high or excessively low, such may influence the terminalgroups of the carbonate oligomer obtainable in the after-mentionedoligomerization step, and as a result, the polycondensation reactiontends to be abnormal.

(Oligomerization Step)

Then, in the oligomerization step, in a predetermined reactor, thealkaline aqueous solution of the dihydroxy compound prepared in the rawmaterial preparation step and phosgene (CDC) are subjected to a phosgenereaction of the dihydroxy compound in the presence of an organic solventsuch as methylene chloride (CH₂Cl₂).

Then, to the mixed liquid after the phosgene reaction of the dihydroxycompound, a condensation catalyst such as triethylamine (TEA) and achain stopper such as p-t-butyl phenol (pTBP) are added, to carry out anoligomerization reaction of the dihydroxy compound.

Then, after further oligomerization reaction is allowed to proceed, theoligomerization reaction liquid of the dihydroxy compound is introducedinto a predetermined static separation tank, an organic phase containingthe carbonate oligomer and an aqueous phase are separated, and theseparated organic phase is supplied to a polycondensation step.

Here, the retention time in the oligomerization step after the alkalineaqueous solution of the dihydroxy compound is supplied to the reactor inwhich the phosgene reaction of the dihydroxy compound is carried outuntil the oligomerization reaction liquid enters the static separationtank, is usually at most 120 minutes, preferably from 30 to 60 minutes.

(Phosgene)

Phosgene used in the oligomerization step is usually used in the form ofliquid or gas. The preferred amount of use of CDC in the oligomerizationstep is properly selected depending upon the reaction conditions,particularly the reaction temperature and the concentration of thedihydroxy compound in the aqueous phase and is not particularly limited.Usually, the amount of CDC is from 1 to 2 mol, preferably from 1.05 to1.5 mol, per 1 mol of the dihydroxy compound. If the amount of use ofCDC is excessively large, unreacted CDC tends to increase, and the unitsmay remarkably be deteriorated. Further, if the amount of use of CDC isexcessively small, the chloroformate group amount tends to beinsufficient, and no appropriate molecular weight elongation tends to beconducted.

(Organic Solvent)

In the oligomerization step, usually an organic solvent is used. Theorganic solvent may be any optional inert organic solvent in whichphosgene and reaction products such as the carbonate oligomer and thepolycarbonate resin are dissolved under the reaction temperature and thereaction pressure in the oligomerization step, and which is not misciblewith water (or which does not form a solution with water).

Such an inert organic solvent may, for example, be an aliphatichydrocarbon such as hexane or n-heptane; a chlorinated aliphatichydrocarbon such as dichloromethane, chloroform, carbon tetrachloride,dichloroethane, trichloroethane, tetrachloroethane, dichloropropane or1,2-dichloroethylene; an aromatic hydrocarbon such as benzene, tolueneor xylene, a chlorinated aromatic hydrocarbon such as chlorobenzene,o-dichlorobenzene or chlorotoluene; or a substituted aromatichydrocarbon such as nitrobenzene or acetophenone.

Among them, a chlorinated hydrocarbon such dichloromethane orchlorobenzene is suitably used. Such an inert organic solvent may beused alone or as a mixture with another solvent.

(Condensation Catalyst)

The oligomerization reaction may be carried out in the presence of acondensation catalyst. The timing of addition of the condensationcatalyst is preferably after CDC is consumed. The condensation catalystmay optionally be selected among many condensation catalysts which havebeen used for a two-phase interfacial condensation method. It may, forexample, be trialkylamine, M-ethylpyrrolidone, N-ethylpiperidine,N-ethylmorpholine, N-isopropylpiperidine or N-isopropylmorpholine. Amongthem, triethylamine or N-ethylpiperidine is preferred.

(Chain Stopper)

In this embodiment, in the oligomerization step, usually a monophenol isused as the chain stopper. The monophenol may, for example, be phenol; aC₁₋₂₀ alkylphenol such as p-t-butylphenol or p-cresol; or a halogenatedphenol such as p-chlorophenol or 2,4,6-tribromophenol. The amount of useof the monophenol is properly selected depending upon the molecularweight of the obtainable carbonate oligomer, and is usually from 0.5 to10 mol % based on the dihydroxy compound.

In the interfacial method, the molecular weight of the polycarbonateresin is determined by the amount of addition of the chain stopper suchas the monophenol. Accordingly, the timing of addition of the chainstopper is preferably between immediately after completion ofconsumption of the carbonate-forming compound and before the molecularweight elongation starts, with a view to controlling the molecularweight of the polycarbonate resin.

If the monophenol is added when the carbonate-forming compound coexists,a condensate of the monophenol (a diphenyl carbonate) forms in a largeamount, and no polycarbonate resin having a desired molecular weighttends to be obtained. If the timing of addition of the monophenol is toolate, there may be such drawbacks that the molecular weight controltends to be difficult, the obtainable resin may have a specific shoulderon the low molecular side in the molecular weight distribution, andsagging may occur at the time of molding.

(Branching Agent)

Further, in the oligomerization step, an optional branching agent may beused. Such a branching agent may, for example, be2,4-bis(4-hydroxyphenylisopropyl)phenol,2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol,2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane or1,4-bis(4,4′-dihydroxytriphenylmethyl)benzene. Further,2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride or the likemay also be used. Among them, a branching agent having at least threephenolic hydroxy groups is suitable. The amount of use of the branchingagent is properly selected depending upon the degree of branching of theobtainable carbonate oligomer, and is usually from 0.05 to 2 mol % basedon the dihydroxy compound.

In the oligomerization step, in a case where the two-phase interfacialcondensation method is employed, it is preferred that prior to contactof the aqueous solution of the metal compound of the dihydroxy compoundwith phosgene, the organic phase containing the dihydroxy compound, thephase containing the metal compound are brought into contact with anorganic phase not optionally mixed with water, to form an emulsion.

As a means of forming such an emulsion, it is preferred to use, forexample, a mixing machine such as a stirring machine having apredetermined stirring blade, a dynamic mixer such as a homogenizer, ahomomixer, a colloid mill, a flow jet mixer or an ultrasonic emulsifier,or a static mixer. The emulsion usually has a droplet size of from 0.01to 10 μm, and has emulsion stability.

The emulsified state of the emulsion is usually represented by the Webernumber or P/q (driver power per unit volume). The Weber number ispreferably at least 10,000, more preferably at least 20,000, mostpreferably at least 35,000. Further, as the upper limit, at a level ofat most 1,000,000 is enough. Further, P/q is preferably at least 200kg·m/L, more preferably at least 500 kg·m/L, most preferably at least1,000 kg·m/L.

Contact of the emulsion with CDC is preferably carried out under mixingconditions weaker than the above-described emulsifying conditions, witha view to suppressing dissolution of CDC in the organic phase. The Webernumber is less than 10,000, preferably less than 5,000, more preferablyless than 2,000. Further, P/q is less than 200 kg·m/L, preferably lessthan 100 kg·m/L, more preferably less than 50 kg·m/L. Contact with CDCcan be achieved by introducing CDC into a tubular reactor or a tank-formreactor.

The reaction temperature in the oligomerization step is usually at most80° C., preferably at most 60° C., further preferably within a range offrom 10 to 50° C. The reaction time is properly selected depending uponthe reaction temperature, and is usually from 0.5 minute to 10 hours,preferably from 1 minute to 2 hours. If the reaction temperature isexcessively high, the side reaction cannot be controlled, and the CDCunits tend to be deteriorated. If the reaction temperature isexcessively low, although such is preferred with a view to controllingthe reaction, the refrigeration load tends to increase, thus leading tothe cost increases.

The carbonate oligomer concentration in the organic phase may be such arange that the obtainable carbonate oligomer is soluble, andspecifically, it is at a level of from 10 to 40 wt %. The proportion ofthe organic phase is preferably from 0.2 to 1.0 by the volume ratiobased on the aqueous phase containing the aqueous solution of the metalcompound salt of the dihydroxy compound.

(Polycondensation Step)

Then, in the polycondensation step, the organic phase containing thecarbonate oligomer separated from the aqueous phase in the staticseparation tank is transferred to an oligomer tank having a stirringmachine. In the oligomer tank, a condensation catalyst such astriethylamine (TEA) is further added.

Then, the organic phase stirred in the oligomer tank is introduced intoa predetermined polycondensation reaction tank, and then to thepolycondensation reaction tank, demineralized water (DMW), an organicsolvent such as methylene chloride (CH₂Cl₂) and a sodium hydroxideaqueous solution are supplied, stirred and mixed to carry out apolycondensation reaction of the carbonate oligomer.

The polycondensation reaction liquid in the polycondensation reactiontank is then continuously introduced successively to a plurality ofpolycondensation reaction tanks, whereby the polycondensation reactionof the carbonate oligomer is completed.

Here, in the polycondensation step, the retention time in thepolycondensation reaction tanks in which the polycondensation reactionof the carbonate oligomer is continuously carried out is usually at most12 hours, preferably from 0.5 to 5 hours.

As a preferred embodiment of the polycondensation step, first, theorganic phase containing the carbonate oligomer and the aqueous phaseare separated, and as the case requires, an inert organic solvent isadded to the separated organic phase to adjust the concentration of thecarbonate oligomer. In such a case, the amount of the inert organicsolvent is adjusted so that the concentration of the polycarbonate resinin the organic phase obtainable by the polycondensation reaction is from5 to 30 wt %. Then, water and an aqueous solution containing an alkalimetal compound or an alkaline earth metal compound are newly added, andfurther, to adjust the polycondensation conditions, preferably acondensation catalyst is added, and the polycondensation reaction iscarried out in accordance with the interfacial polycondensation method.The ratio of the organic phase to the aqueous phase in thepolycondensation reaction is preferably such that the organic phase:theaqueous phase=1:0.2 to 1:1 by the volume ratio.

As the metal compound, the same compound as one used in theabove-described oligomerization step may be mentioned. Particularly,sodium hydroxide is industrially preferred. The amount of use of themetal compound may be at least an amount with which the reaction systemis always alkaline during the polycondensation reaction, and the entireamount may be added all at once at the start of the polycondensationreaction, or the metal compound may be added as properly divided duringthe polycondensation reaction.

If the amount of use of the metal compound is excessively large, ahydrolysis reaction as a side reaction tends to proceed. Accordingly,the concentration of the metal compound contained in the aqueous phaseafter completion of the polycondensation reaction is preferably adjustedto be at least 0.05 N, preferably at a level of from 0.05 to 0.3 N.

The temperature of the polycondensation reaction in the polycondensationstep is usually in the vicinity of room temperature. The reaction timeis from 0.5 hour to 5 hours, preferably at a level of from 1 to 3 hours.

(Washing Step)

Then, after completion of the polycondensation reaction in thepolycondensation reaction tanks, the polycondensation reaction liquid issubjected to alkali washing with an alkaline washing liquid, acidwashing with an acid washing liquid and water washing with washing waterby a known method. The entire retention time in the washing step isusually at most 12 hours, preferably from 0.5 to 6 hours.

(Polycarbonate Resin Isolation Step)

In the polycarbonate resin isolation step, first, the polycondensationreaction liquid containing the polycarbonate resin washed in the washingstep is concentrated to a predetermined solid content concentration toprepare a concentrated liquid. The solid content concentration of thepolycarbonate resin in the concentrated liquid is usually from 5 to 35wt %, preferably from 10 to 30 wt %.

Then, the concentrated liquid is continuously supplied to apredetermined granulation tank, and stirred and mixed with demineralizedwater (DMW) of a predetermined temperature. Further, a granulationtreatment of evaporating the organic solvent while maintaining thesuspended state in water is carried out to form a water slurrycontaining polycarbonate resin granules.

Here, the temperature of demineralized water (DMW) is usually from 37 to67° C., preferably from 40 to 50° C. Further, the solidificationtemperature of the polycarbonate resin by the granulation treatmentcarried out in the granulation tank is usually from 37 to 67° C.,preferably from 40 to 50° C.

The water slurry containing a polycarbonate resin powder continuouslydischarged from the granulation tank is then continuously introducedinto a predetermined separator, and water is separated from the waterslurry.

(Drying Step)

In the drying step, the polycarbonate resin powder after water isseparated from the water slurry in the separator, is continuouslysupplied to a predetermined drying machine, made to stay in apredetermined retention time and then continuously withdrawn. The dryingmachine may, for example, be a fluidized bed drying machine. Further, aplurality of fluidized bed drying machines may be connected in series tocarry out the drying treatment continuously.

Here, the drying machine usually has a heating means such as a heatmedium jacket, and is maintained usually at from 0.1 to 1.0 MPa-G,preferably from 0.2 to 0.6 MPa-G, for example, by water vapor, wherebythe temperature of nitrogen (N₂) which flows in the drying machine ismaintained usually at from 100 to 200° C., preferably from 120 to 180°C.

<Melt Method>

Now, the melt method will be described.

(Dihydroxy Compound)

The dihydroxy compound as a material of the polycarbonate resin of thepresent invention may be the same dihydroxy compound or the like asdescribed in the interfacial method.

(Carbonic Diester)

The carbonic diester as the material of the polycarbonate resin of thepresent invention may be a compound represented by the following formula(14).

In the formula (14), A′ is a C₁₋₁₀ linear, branched or cyclic monovalenthydrocarbon group which may be substituted. Two A's may be the same ordifferent.

Furthermore, examples of a substituent in the A′ include a halogen atom,a C₁₋₁₀ alkyl group, a C₁₋₁₀ alkoxy group, a phenyl group, a phenoxygroup, a vinyl group, a cyano group, an ester group, an amide group anda nitro group.

Specific examples of the carbonic diester compound include diphenylcarbonate, a substituted diphenyl carbonate such as ditolyl carbonate, adialkyl carbonate such as dimethyl carbonate, diethyl carbonate anddi-t-butyl carbonate.

Among them, diphenyl carbonate (hereinafter sometimes referred to as“DPC”) and a substituted diphenyl carbonate are preferred. Thosecarbonic diesters may be used alone or as a mixture of two or more ofthem.

Furthermore, the carbonic diester compound may be replaced by adicarboxylic acid or a dicarboxylate in an amount of preferably at most50 mol %, more preferably at most 30 mol %.

The representative examples of the dicarboxylic acid or dicarboxylateinclude terephthalic acid, isophthalic acid, diphenyl terephthalate anddiphenyl isophthalate. When the carbonic diester is replaced by such adicarboxylic acid or a dicarboxylate, a polyester carbonate is obtained.

In the process for producing the polycarbonate resin of the presentinvention by the melt method, as the amount of use of those carbonicdiesters (including the above substitutional dicarboxylic acid ordicarboxylate; the same applies hereinafter), the carbonic diestercompound is used in a molar ratio of usually from 1.01 to 1.30 mol,preferably from 1.02 to 1.20 mol per 1 mol of the dihydroxy compound. Ifthe molar ratio of the carbonic diester is excessively low, the esterexchange reaction rate tends to be lowered, whereby production of apolycarbonate resin having a desired molecular weight is difficult, orthe terminal hydroxy group concentration of the obtainable polycarbonateresin tends to be high, thus deteriorating the thermal stability.Further, if the molar ratio of the carbonic diester is excessively high,the ester exchange reaction rate tends to be decreased, and productionof a polycarbonate resin having a desired molecular weight tends to bedifficult, and in addition, an amount of the carbonic diester compoundremaining in the resin becomes so large as to produce an unpleasant odorduring the forming process or from a molded article, which isundesirable.

(Ester Exchange Catalyst)

The ester exchange catalyst used in the process for producing thepolycarbonate resin of the present invention by the melt method, may beone of catalysts generally used in producing a polycarbonate resin by anester exchange method, and is not particularly limited.

In general, examples of the catalyst include basic compounds such as analkali metal compound, an alkaline earth metal compound, a berylliumcompound, a magnesium compound, a basic boron compound, a basicphosphorus compound, a basic ammonium compound, and an amine compound.Among them, an alkali metal compound or an alkaline earth metal compoundis practically preferred. Those ester exchange catalysts may be usedalone or as a mixture of two or more of them.

The amount of use of the ester exchange catalyst is usually within arange of from 1×10⁻⁹ to 1×10⁻³ mol per 1 mol of the entire dihydroxycompound. In order to obtain a polycarbonate resin excellent in themoldability and the hue, the amount of the ester exchange catalyst is,when an alkali metal compound and/or an alkaline earth metal compound isused, preferably within a range of from 1.0×10⁻⁸ to 1×10⁻⁴ mol, morepreferably within a range of from 1.0×10⁻⁸ to 1×10⁻⁵ mol, particularlypreferably within a range of from 1.0×10⁻⁷ to 5.0×10⁻⁶ mol, per 1 mol ofall the dihydroxy compounds. If the amount is smaller than the abovelower limit, no polymerization activity necessary to produce apolycarbonate resin having a desired molecular weight will be obtained,and if it is larger than the above upper limit, the polymer hue may bedeteriorated, or the amount of the branching component tends to be toomany, thus leading to a decrease in the fluidity, whereby no desiredpolycarbonate resin having excellent melt properties will be obtained.

Examples of the alkali metal compound include inorganic alkali metalcompounds such as hydroxides, carbonates and hydrogen carbonatecompounds of alkali metals; and organic alkali metal compounds such assalts of alkali metals with alcohols, phenols or organic carboxylicacids. Examples of the alkali metals include lithium, sodium, potassium,rubidium and cesium.

Among such alkali metal compounds, a cesium compound is preferred, andcesium carbonate, cesium hydrogen carbonate and cesium hydroxide areparticularly preferred.

Examples of the alkaline earth metal compound include inorganic alkalineearth metal compounds such as hydroxides or carbonates of alkaline earthmetals; and salts of alkaline earth metals with alcohols, phenols ororganic carboxylic acids. Examples of the alkaline earth metals includecalcium, strontium and barium.

Further, examples of the beryllium compound and magnesium compoundinclude inorganic metal compounds such as hydroxides or carbonates ofthe metals; and salts of those metals with alcohols, phenols or organiccarboxylic acids.

Examples of the basic boron compound include a sodium salt, a potassiumsalt, a lithium salt, a calcium salt, a magnesium salt, a barium saltand a strontium salt of a boron compound. Examples of the boron compoundinclude tetramethyl boron, tetraethyl boron, tetrapropyl boron,tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron,trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron,triethylphenyl boron, tributylbenzyl boron, tributylphenyl boron,tetraphenyl boron, benzyltriphenyl boron, methyltriphenyl boron andbutyltriphenyl boron.

Examples of the basic phosphorus compound include trivalent phosphoruscompounds such as triethylphosphine, tri-n-propylphosphine,triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine andtributylphosphine; and quaternary phosphonium salts derived from thosecompounds.

Examples of the basic ammonium compound include tetramethylammoniumhydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide,tetrabutylammonium hydroxide, trimethylethylammonium hydroxide,trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide,triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide,triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide,tributylphenylammonium hydroxide, tetraphenylammonium hydroxide,benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide andbutyltriphenylammonium hydroxide.

Examples of the amine compound include 4-aminopyridine, 2-aminopyridine,N,N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine,2-methoxypyridine, 4-methoxypyridine, 2-dimethylaminoimidazole,2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazoleand aminoquinoline.

(Catalyst Deactivating Agent)

In the present invention, after completion of the ester exchangereaction, a catalyst deactivating agent to neutralize and deactivate theester exchange catalyst may be added. The heat resistance and thehydrolysis resistance of a polycarbonate resin obtained by such atreatment will be improved.

Such a catalyst deactivating agent is preferably an acidic compoundhaving pKa of at most 3, such as sulfonic acid or a sulfonate, and itmay, for example, be specifically benzenesulfonic acid,p-toluenesulfonic acid, methyl benzenesulfonate, ethyl benzenesulfonate,propyl benzenesulfonate, butyl benzenesulfonate, methylp-toluenesulfonate, ethyl p-toluenesulfonate, propyl p-toluenesulfonateor butyl p-toluenesulfonate.

Among them, p-toluenesulfonic acid or butyl p-toluenesulfonate issuitably used.

The process for producing the polycarbonate resin by the melt method isconducted by preparing a material mixture melt containing the dihydroxycompound and the carbonic diester as materials (raw material preparationstep) and subjecting the material mixture melt to a multi-stagepolycondensation reaction in a molten state in the presence of an esterexchange reaction catalyst using a plurality of reaction tanks(polycondensation step). The reaction method may be any of a batchwisemethod, a continuous method and a combination of a batchwise method anda continuous method. As the reaction tanks, a plurality of verticalstirring reaction tanks and as the case requires, at least onehorizontal stirring reaction tank successive thereto are used. Usually,these reaction tanks are connected in series to carry out the treatmentcontinuously.

After the polycondensation step, a step of terminating the reaction andevaporating and removing unreacted materials and reaction by-products inthe polycondensation reaction liquid, a step of adding a thermalstabilizer, a mold release agent, a colorant or the like, a step offorming the polycarbonate resin into a predetermined particle size, orthe like may properly be added.

Now, the respective steps in the production process will be describedbelow.

(Raw Material Preparation Step)

The dihydroxy compound and the carbonic diester compound used as rawmaterials of the polycarbonate resin are generally prepared as amaterial mixture melt using a batchwise, semibatchwise or continuousstirring tank type apparatus in an atmosphere of an inert gas such asnitrogen or argon. In the case of using bisphenol A as the dihydroxycompound and diphenyl carbonate as the carbonic diester, for example, atemperature of the molten mixture is selected from a range of usuallyfrom 120 to 180° C., preferably from 125 to 160° C.

Now, a case of using bisphenol A as the dihydroxy compound and diphenylcarbonate as the carbonic diester as materials will be described as anexample.

In this case, the ratio of the dihydroxy compound to the carbonicdiester is adjusted so that the carbonic diester is in excess, and thecarbonic diester compound is in a proportion of usually from 1.01 to1.30 mol, preferably from 1.02 to 1.20 mol, per 1 mol of the dihydroxycompound.

(Polycondensation Step)

Polycondensation of an ester exchange reaction between the dihydroxycompound and the carbonic diester compound is continuously conducted bya multiple-stage method of generally at least two stages, preferablyfrom 3 to 7 stages. Specific reaction conditions of each stage are asfollows: the temperature is from 150 to 320° C., the pressure is fromordinary pressure to 0.01 Torr (1.3 Pa), and the average residence timeis from 5 to 150 minutes.

The temperature and vacuum are generally set to become higher stepwisewithin the above reaction conditions in each of the reaction tanks ofthe multi-stage method, in order to effectively discharge themonohydroxy compound such as phenol produced as a by-product with theprogress of the ester exchange reaction.

When the polycondensation step is conducted by the multi-stage method,it is preferred to provide a plurality of reaction tanks includingvertical stirring reaction tanks to increase the average molecularweight of the polycarbonate resin. The number of reaction tanks isusually from 2 to 6, preferably from 4 to 5.

Here, the reaction tanks may, for example, be stirring tank typereaction tanks, thin-film reaction tanks, centrifugal thin-filmevaporation reaction tanks, surface renewal type twin screw kneadingreaction tanks, twin screw horizontal stirring reaction tanks, wet walltype reaction tanks, porous plate type reaction tanks in whichpolycondensation proceeds during a free fall, and porous plate typereaction tanks provided with a wire, in which polycondensation proceedsduring a fall along a wire.

Examples of the type of the stirring blade in the vertical stirringreaction tanks include a turbine blade, a paddle blade, a Pfaudlerblade, an anchor blade, a FULLZONE blade (manufactured by KobelcoEco-Solutions Co., Ltd.), a SANMELLER blade (manufactured by MITSUBISHIHEAVY INDUSTRIES, LTD.), a MAXBLEND blade (manufactured by SHIMechanical & Equipment Inc.), a helicalribbon blade, and a lattice typetwisting blade (manufactured by Hitachi Plant Technologies, Ltd.).

Further, the horizontal stirring reaction tank refers to a reaction tankwith a stirring blade a revolution axis of which is horizontal(horizontal direction). Examples of the stirring blade in the horizontalstirring reaction tank include single shaft stirring blades such as adisk type and a paddle type, and two shaft stirring blades such as HVR,SCR and N-SCR (manufactured by MITSUBISHI HEAVY INDUSTRIES, LTD.),Bivolak (manufactured by SHI Mechanical & Equipment Inc.), and aspectacle-shaped blade and a lattice type blade (manufactured by HitachiPlant Technologies, Ltd.).

Further, the ester exchange catalyst used for the polycondensation ofthe dihydroxy compound and the carbonic diester compound may begenerally previously prepared as an aqueous solution. The concentrationof the catalyst solution is not particularly limited, and it is adjustedto an optional concentration according to the solubility of the catalystin the solvent. As the solvent, acetone, an alcohol, toluene, phenol,water or the like may properly be selected.

In a case where water is selected as the solvent of the catalyst, theproperties of the water are not particularly limited so long as kindsand concentrations of impurities contained therein are constant.Usually, distilled water, deionized water or the like is preferablyused.

<Method for Producing Polycarbonate Resin Composition>

The method for producing the polycarbonate resin composition comprisingthe polycarbonate resin (a) and the polycarbonate resin (b) of thepresent invention is not particularly limited and may, for example, be

(1) a method of melt-kneading the polycarbonate resin (a) and thepolycarbonate resin (b):

(2) a method of melt-kneading the polycarbonate resin (a) in a moltenstate and the polycarbonate resin (b) in a molten state;

(3) a method of mixing the polycarbonate resin (a) and the polycarbonateresin (b) in a solution state, or

(4) a method of dry-blending a polycarbonate resin (a) and thepolycarbonate resin (b).

Now, the respective methods will be described.

(1) Method of Melt-Kneading Polycarbonate Resin (a) and PolycarbonateResin (b)

Pellets or granules of the polycarbonate resin (a) and pellets orgranules of the polycarbonate resin (b) are melt-kneaded by using amixing apparatus such as a kneader, a twin screw extruder or a singlescrew extruder. The pellets or granules of the polycarbonate resin (a)and the pellets or granules of the polycarbonate resin (b) maypreliminarily be mixed in a solid state and then kneaded, or either oneof them is preliminarily melted in the above mixing apparatus, and theother polycarbonate resin is added and kneaded. The temperature at whichthey are kneaded is not particularly limited, and is preferably at least240° C., more preferably at least 260° C., further preferably at least280° C.

Further, it is preferably at most 350° C., particularly preferably atmost 320° C. If the kneading temperature is too low, mixing of thepolycarbonate resin (a) and the polycarbonate resin (b) will not becomplete, and when a molded article is molded, there may be dispersionof the hardness or the impact resistance, such being unfavorable.Further, if the kneading temperature is too high, the color of thepolycarbonate resin composition may be deteriorated, such beingunfavorable.

(2) Method of Melt-Kneading Polycarbonate Resin (a) in Molten State andPolycarbonate Resin (b) in Molten State

The polycarbonate resin (a) in a molten state and the polycarbonateresin (b) in a molten state are mixed by means of a mixing apparatussuch as a stirring tank, a static mixer, a kneader, a twin screwextruder or a single screw extruder. In this case, for example, apolycarbonate resin obtained by the melt polymerization method may beintroduced into the above mixing apparatus in a molten state withoutcooling and solidification. The mixing temperature is not particularlylimited, and is preferably at least 150° C., more preferably at least180° C., further preferably at least 200° C. Further, it is preferablyat most 300° C., particularly preferably at most 250° C. If the mixingtemperature is low, mixing of the polycarbonate resin (a) and thepolycarbonate resin (b) will not be complete, and when a molded articleis molded, there may be dispersion of the hardness or the impactresistance, such being unfavorable. Further, if the mixing temperatureis too high, the color of the polycarbonate resin composition may bedeteriorated, such being unfavorable.

(3) Method of Mixing Polycarbonate Resin (a) and Polycarbonate Resin (b)in Solution State

The polycarbonate resin (a) and the polycarbonate resin (b) aredissolved in an appropriate solvent to form solutions, they are mixed ina solution state and then a polycarbonate resin composition is isolated.Such a proper solvent may, for example, be an aliphatic hydrocarbon suchas hexane or n-heptane; a chlorinated aliphatic hydrocarbon such asdichloromethane, chloroform, carbon tetrachloride, dichloroethane,trichloroethane, tetrachloroethane, dichloropropane or1,2-dichloroethylene; an aromatic hydrocarbon such as benzene, tolueneor xylene; or a substituted aromatic hydrocarbon such as nitrobenzene oracetophenone. Among them, a chlorinated hydrocarbon such asdichloromethane or chlorobenzene is suitably used. Such a solvent may beused alone or as a mixture with another solvent.

The mixing apparatus may, for example, be a stirring tank or a staticmixer. Further, the mixing temperature is not particularly limited solong as the polycarbonate resin (a) and the polycarbonate resin (b) aresoluble, and is usually at most the boiling point of the solvent used.

(4) Method of Dry-Blending Polycarbonate Resin (a) and PolycarbonateResin (b)

Pellets or granules of the polycarbonate resin (a) and pellets orgranules of the polycarbonate resin (b) are dry-blended by using atumbler, a super mixer, a Henschel mixer, a nauta mixer or the like.

Among the above methods (1) to (4), preferred are the methods (1) and(2) of melt-kneading the polycarbonate resin (a) and the polycarbonateresin (b) and the method (4) of dry-blending the polycarbonate resin (a)and the polycarbonate resin (b).

In production of the polycarbonate resin composition of the presentinvention, in any of the above methods, a pigment, a dye, a mold releaseagent, a thermal stabilizer or the like may properly be added within arange not to impair the objects of the present invention.

(Flame Retardant)

The flame retardant used in this embodiment may, for example, be atleast one member selected from the group consisting of a metal sulfonatetype flame retardant, a halogen-containing compound type flameretardant, a phosphorus-containing compound type flame retardant and asilicon-containing compound type flame retardant. Among them, a metalsulfonate type flame retardant is preferred.

The blending amount of the flame retardant used in this embodiment isusually from 0.01 to 1 part by weight, preferably from 0.05 to 1 part byweight per 100 parts by weight of the polycarbonate resin.

The metal sulfonate type flame retardant may, for example, be a metalaliphatic sulfonate or a metal aromatic sulfonate. The metal of such ametal salt may, for example, be an alkali metal such as sodium, lithium,potassium, rubidium or cesium; beryllium or a magnesium such asmagnesium; or an alkaline earth metal such as calcium, strontium orbarium. The metal sulfonate may be used alone or as a mixture of two ormore.

The metal sulfonate may, for example, be a metal aromatic sulfonesulfonate or a metal perfluoroalkane sulfonate.

The metal aromatic sulfone sulfonate may, for example, be specificallysodium diphenylsulfone-3-sulfonate, potassiumdiphenylsulfone-3-sulfonate, sodium4,4′-dibromodiphenyl-sulfone-3-sulfonate, potassium4,4′-dibromodiphenyl-sulfone-3-sulfone, calcium4-chloro-4′-nitrodiphenylsulfone-3-sulfonate, disodiumdiphenylsulfone-3,3′-disulfonate or dipotassiumdiphenylsulfone-3,3′-disulfonate.

The metal perfluoroalkane sulfonate may, for example, be sodiumperfluorobutane sulfonate, potassium perfluorobutane sulfonate, sodiumperfluoromethylbutane sulfonate, potassium perfluoromethylbutanesulfonate, sodium perfluorooctane sulfonate, potassium perfluorooctanesulfonate or a tetraethylammonium salt of perfluorobutane sulfonate.

The halogen-containing compound type flame retardant may, for example,be specifically tetrabromobisphenol A, tribromophenol, brominatedaromatic triazine, a tetrabromobisphenol A epoxy oligomer, atetrabromobisphenol A epoxy polymer, decabromodiphenyl oxide,tribromoallyl ether, a tetrabromobisphenol A carbonate oligomer,ethylenebistetrabromophthalimide, decabromodiphenylethane, brominatedpolystyrene or hexabromocyclododecane.

The phosphorus-containing compound type flame retardant may, forexample, be red phosphorus, covered red phosphorus, a polyphosphatecompound, a phosphate compound or a phosphazene compound. Among them,the phosphate compound may, for example, be specifically trimethylphosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate,tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate,cresyldiphenyl phosphate, octyldiphenyl phosphate, diisopropylphenylphosphate, tris(chloroethyl)phosphate, tris(dichloropropyl)phosphate,tris(chloropropyl)phosphate, bis(2,3-dibromopropyl)-2,3-dichloropropylphosphate, tris(2,3-dibromopropyl)phosphate, bis(chloropropyl)monooctylphosphate, bisphenol A bisphosphate, hydroquinone bisphosphate, resorcinbisphosphate or trioxybenzene triphosphate.

The silicon-containing compound type flame retardant may, for example,be silicone varnish, a silicone resin wherein substituents bonded tosilicon atoms are an aromatic hydrocarbon group and an aliphatichydrocarbon group having at least 2 carbon atoms, a silicone compoundhaving a branched main chain and having an aromatic group in the organicfunctional group contained, a silicone powder having apolydiorganosiloxane polymer which may have functional groups supportedon the surface of a silica powder, or anorganopolysiloxane-polycarbonate copolymer.

The polycarbonate resin composition to which this embodiment isapplicable, which comprises a combination of the polycarbonate resinhaving structural units represented by the above formula (1) and theflame retardant, has flame retardancy improved as compared with a resincomposition using a polycarbonate resin obtainable by using bisphenol Aas a raw material monomer (hereinafter referred to as “A-PC”).

The reason why the flame retardancy of the polycarbonate resincomposition to which this embodiment is applicable is improved is notclearly understood, but is considered to be as follows, with referenceto a case of using a polycarbonate resin obtained by using2,2-bis(3-methyl-4-hydroxyphenyl)propane which is an aromatic dihydroxycompound as the raw material monomer (hereinafter referred to as “C-PC”)as the polycarbonate resin component, as an example.

That is, C-PC has a low thermal decomposition starting temperature ascompared with A-PC and is likely to be decomposed. Thus, C-PC is quicklydecomposed and graphitized, thus forming a heat insulating layer (char),whereby flame retardancy is easily attained. The low thermaldecomposition starting temperature of C-PC as compared with A-PC isinfluenced by the difference in the structure of the bisphenol structurethat “the 3-position of each of the two benzene rings is substituted bya methyl group”. Particularly in a case where C-PC is produced by theabove-described melt method, when the polymerization reaction proceedsin a molten state at high temperature and at high shear strength, abranch is likely to form from the 3-position of each of the phenyl ringsof the bisphenol compound. Accordingly, the flame retardancy is improvedsuch that in a flame test, flaming drips are suppressed.

Further, C-PC has a lowered packing density of molecular chains ascompared with A-PC and has molecular chains which are rigid and hardlymove, and thus the molded article of resin tends to have a low shrinkageand a low linear expansion coefficient. Thus, high dimensional stabilityof the molded article of resin is expected.

The polycarbonate resin composition to which this embodiment isapplicable, which has such properties, is suitable for resin members forwhich high dimensional accuracy is required, such as chassis forprecision instruments such as cellular phones and PCs; housing for homeelectric appliances such as TVs; screen films; exterior members of amulticolor molded article of resin of two or more colors, such asglazing; and multilayered extruded articles having at least two surfacelayers of building materials such as carports, agricultural greenhousesand acoustic insulation boards.

Further, the polycarbonate resin composition to which this embodiment isapplicable, with which a molded article of resin having high hardnessand improved flame retardancy can be obtained, is suitable forapplications of e.g. molded articles of resin related to illuminationsuch as LED, such as lamp lenses, protective covers and diffusers;lenses for glasses, vending machine buttons, and keys of e.g. mobiledevices.

With the polycarbonate resin composition to which this embodiment isapplicable, various additives are blended as the case requires. Theadditives may, for example, be a stabilizer, an ultraviolet absorber, amold release agent, a colorant, an antistatic agent, a thermoplasticresin, a thermoplastic elastomer, glass fibers, glass flakes, glassbeads, carbon fibers, Wollastonite, calcium silicate and aluminum boratewhiskers.

The method of mixing the polycarbonate resin and the flame retardant andthe additives or the like blended as the case requires is notparticularly limited. In this embodiment, for example, a method ofmixing the polycarbonate resin in a solid state such as pellets or apowder with the flame retardant and the like, followed by kneading e.g.by an extruder, a method of mixing the polycarbonate resin in a moltenstate and the flame retardant and the like, and a method of adding theflame retardant and the like during the polymerization reaction of theraw material monomer by the melt method or the interfacial method, orwhen the polymerization reaction is completed.

<Method for Producing Molded Article of Polycarbonate Resin>

To produce a molded article of resin from the polycarbonate resincomposition of the present invention, a conventional extruder orinjection molding machine is used.

The molded article of polycarbonate resin of the present invention ispreferably molded by injection molding using an injection moldingmachine, in view of advantages such that molded articles ofpolycarbonate resin having a complicated shape can be molded with a highcycle rate.

The molding temperature is not particularly limited but is preferably atleast 200° C., more preferably at least 250° C., most preferably atleast 280° C. Further, it is preferably at most 350° C., particularlypreferably at most 320° C. If the molding temperature is too low, themelt viscosity tends to be high, the fluidity tends to be decreased, themoldability may be decreased, the effects of improving the surfacehardness may be decreased, and the surface hardness of the obtainableresin composition may be decreased. If the molding temperature is toohigh, the polycarbonate resin will be colored, whereby the color of thepolycarbonate resin composition is also deteriorated in some cases, suchbeing unfavorable.

<Method for Producing Injection-Molded Article>

To produce an injection-molded article from the polycarbonate resincomposition of the present invention, a conventional injection moldingmachine is used.

When an injection molding machine or the like is used, the moldtemperature is not particularly limited but is preferably at most 150°C., more preferably at most 120° C., most preferably at most 100° C.Further, it is preferably at least 30° C., particularly preferably atleast 50° C. If the mold temperature is too high, the cooling time atthe time of molding is required to be long, whereby the cycle ofproduction of the molded article tends to be long, thus decreasing theproductivity in some cases. If the mold temperature is too low, the meltviscosity of the resin composition tends to be too high, whereby nouniform molded article may be obtained, and problems may arise such thatthe molded article surface is non-uniform, such being unfavorable.

<Method for Producing Extruded Article>

To produce an extruded article from the polycarbonate resin compositionof the present invention, a conventional extruder is used. The extruderis usually provided with a T-die, a round die or the like, and extrudedarticles of various shapes can be obtained. The obtained extrudedarticle may, for example, be a sheet, a film, a plate, a tube or a pipe.Among them, a sheet or a film is preferred.

In order to improve the adhesion, coating properties and printingproperties of the extruded article of the polycarbonate resincomposition of the present invention, a hard coating layer may belaminated on both sides or one side of the extruded article, a weatherresistance and/or scratch resistance improving film may beheat-laminated on both sides or one side of the extruded article, orembossing or translucent or opaque treatment may be applied to thesurface.

Further, when injection molding or extrusion is carried out, a pigment,a dye, a mold release agent, a thermal stabilizer or the like mayproperly be added within a range not to impair the objects of thepresent invention.

The above-mentioned molded article may be used in various fields ofbuildings, vehicles, electric/electronic devices, machines and others.

<Flame Retardancy of Molded Article of Polycarbonate Resin>

A molded article of polycarbonate resin is prepared by using thepolycarbonate resin composition to which this embodiment is applicableas described above. The method of molding the molded article ofpolycarbonate resin is not particularly limited, and for example, amolding method using a conventional molding machine such as an injectionmolding machine may be mentioned. The molded article of polycarbonateresin to which this embodiment is applicable has a decrease in thesurface hardness and the transparency suppressed and has favorable flameretardancy, as compared with a case of using, for example, apolycarbonate resin obtainable by using e.g. bisphenol A having nosubstituent on the phenyl group as a monomer.

Specifically, the molded article of polycarbonate resin to which thisembodiment is applicable, with respect to the flame retardancy,preferably satisfies the classification V-0 in a flammability test ofUL94 with respect to a test specimen having a thickness of at most 2 mm.With respect to the transparency, the haze is preferably at most 1.0with respect to a test specimen having a thickness of 3 mm in accordancewith JIS K7136.

EXAMPLES

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is not limited to the following Examples. Physical propertiesof polycarbonate resins and compositions used in Examples were evaluatedby the following methods.

(1) Pencil Hardness of Molded Article

Using an injection molding machine J50E2 (manufactured by Japan SteelWorks, Ltd.), a plate (molded article) of a polycarbonate resin or aplate (molded article) of a polycarbonate resin composition of 60 mm×60mm×3 mm in thickness was injection-molded under conditions of a barreltemperature of 280° C. and a mold temperature of 90° C. With respect toeach molded articles, in accordance with ISO 15184 using a pencilhardness tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.), thepencil hardness measured at a load of 750 g was obtained.

(2) Charpy Impact Strength of Polycarbonate Resin or Polycarbonate ResinComposition

Using an injection molding machine J50E2 (manufactured by Japan SteelWorks, Ltd.), a polycarbonate resin or a polycarbonate resin compositionwas molded to obtain a molded specimen under conditions of a barreltemperature of 280° C. and a mold temperature of 90° C. Using thismolded specimen, in accordance with JIS K7111, the Charpy impactstrength was measured with a notch of 0.25 mmR.

(3) Yellowness Index (YI) of Polycarbonate Resin or Polycarbonate ResinComposition

Using the molded article molded in the above (1), the yellowness index(YI) was measured by a spectral colorimeter CM-3700d (manufactured byKONICA MINOLTA HOLDINGS, INC.). The smaller the value, the better thecolor.

(4) Viscosity Average Molecular Weight (Mv)

A polycarbonate resin was dissolved in methylene chloride(concentration: 6.0 g/L), and the specific viscosity (ηsp) at 20° C. wasmeasured by using an Ubbelohde viscosity tube, and the viscosity averagemolecular weight (Mv) was calculated in accordance with the followingformula.ηsp/C+[η](1+0.28ηsp)[η]=1.23×10⁻⁴ Mv ^(0.83)(5) Melt Viscosity

It was measured with respect to a polycarbonate resin or a polycarbonateresin composition dried at 120° C. for 5 hours by using a capillaryrheometer “Capirograph 1C” (manufactured by Toyo Seiki Seisaku-sho,Ltd.) equipped with a die of 1 mm in diameter×30 mm at 280° C. at ashear rate of 122 (sec⁻¹). If this melt viscosity is too high, thefluidity tends to be low, and the flowabilities will be deteriorated,and accordingly it is required to be within an appropriate range.

(6) Pencil Hardness of Extruded Article

A polycarbonate resin or a polycarbonate resin composition having athickness of 240 μm and a width of 140±5 mm was extruded into a sheet(extruded article) by using a 25 mmφ single screw extruder (manufacturedby ISUZU KAKOKI K.K.) under conditions of a barrel temperature of 280°C. and a roll temperature of 90° C. With respect to this extrudedarticle, in accordance with ISO 15184, using a pencil hardness tester(manufactured by Toyo Seiki Seisaku-sho, Ltd.), the pencil hardnessmeasured at a load of 750 g was obtained.

(7) Yellowness Index (YI) of Extruded Article

With respect to the extruded article molded in the above (6), theyellowness index (YI) was measured by a spectral colorimeter CM-3700d(manufactured by KONICA MINOLTA HOLDINGS, INC.). The smaller the value,the better the color.

(8) Pencil Hardness of Polycarbonate Resin Cast Article

In a case where the molecular weight of the polycarbonate resin is lowand a molded article for evaluation of the pencil hardness cannot bemolded by the above-described method (1), an evaluation sample wasprepared as follows.

100 g of a polycarbonate resin was added in a glass vessel equipped witha stirring blade, followed by replacement with nitrogen, and thepressure in the glass vessel was maintained at 101.3 kPa (760 Torr) bythe absolute pressure. The glass vessel was immersed in an oil bathheated at 280° C. to melt the polycarbonate resin. After thepolycarbonate resin was uniformly melted, the molten polycarbonate resinwas taken out from the glass vessel into a stainless steel vat in athickness of about 3 mm and cooled to room temperature. With respect tothe cooled polycarbonate resin, in accordance with ISO 15184, using apencil hardness tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.),the pencil hardness at a load of 750 g was measured.

(9) Glass Transition Temperature (Tg)

Using a differential scanning calorimeter DSC6220 (manufactured by SeikoInstruments Inc.), about 10 mg of a polycarbonate resin sample washeated at a heating rate of 20° C./min and the calorie is measured, andin accordance with JIS K7121, an extrapolated glass transition startingtemperature which is a temperature at the intersection of a lineobtained by extending the base line on the low temperature side to thehigh temperature side and a tangent drawn at a point where the gradientof a curve of the stepwise change portion of glass transition wasmaximum, was obtained. This extrapolated glass transition startingtemperature was regarded as the glass transition temperature (Tg).

(10) Pencil Hardness on the Surface of Molded Article of PolycarbonateResin

A polycarbonate resin or a polycarbonate resin composition was moldedinto a molded article of polycarbonate resin of 60 mm×60 mm×3 mm inthickness by an injection molding machine J50E2 (manufactured by JapanSteel Works, Ltd.) under conditions of a barrel temperature of 280° C.and a mold temperature of 90° C. With respect to the molded article ofpolycarbonate resin, in accordance with ISO 15184, using a pencilhardness tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.), thepencil hardness measured at a load of 750 g was obtained.

(11) Charpy Impact Strength of Molded Article of Polycarbonate Resin

A polycarbonate resin or a polycarbonate resin composition was moldedinto a molded article of polycarbonate resin having a shape based on JISK7111 by using an injection molding machine J50E2 (manufactured by JapanSteel Works, Ltd.) under conditions of a barrel temperature of 280° C.and a mold temperature of 90° C. Using the molded article ofpolycarbonate resin, the Charpy impact strength was measured with anotch of 0.25 mmR in accordance with JIS K7111.

(12) Viscosity Average Molecular Weight (Mv) of Polycarbonate Resin

A polycarbonate resin was dissolved in methylene chloride(concentration: 6.0 g/L), the specific viscosity (ηsp) at 20° C. wasmeasured by using an Ubbelohde viscosity tube, and the viscosity averagemolecular weight (Mv) was calculated in accordance with the followingformula.ηsp/C=[η](1+0.28ηsp)[η]=1.23×10⁻⁴ Mv ^(0.83)(13) Intrinsic Viscosity [η] of Polycarbonate Resin

A polycarbonate resin was dissolved in methylene chloride to form asolution (6.0 g/L). Then, with respect to this solution, the intrinsicviscosity was measured by an Ubbelohde viscosity tube at a temperatureof 20° C.

(14) Content [S] of Structural Units (a) on the Surface of MoldedArticle of Polycarbonate Resin.

A polycarbonate resin or a polycarbonate resin composition was moldedinto a molded article of polycarbonate resin of 60 mm×60 mm×3 mm inthickness by an injection molding machine J50E2 (manufactured by JapanSteel Works, Ltd.) under conditions of a barrel temperature of 280° C.and a mold temperature of 90° C. Then, the molded article ofpolycarbonate resin was immersed in methylene chloride (about 400 g) atroom temperature (25° C.). Five seconds after the start of immersion,the molded article of polycarbonate resin was taken out from methylenechloride to obtain a methylene chloride solution. By means of anevaporator, methylene chloride was removed under reduced pressure fromthe methylene chloride solution to obtain a residue. The residue wasdissolved in deuterochloroform, and the solution was subjected tomeasurement by ¹H-NMR method. From the signal intensity of structuralunits (a) and signal intensities of other structural units in theobtained ¹H-NMR spectrum, the content [S] (wt %) of the structural units(a) on the surface of the molded article of polycarbonate resin wascalculated.

(15) Content [T] of Structural Units (a) in the Entire Molded Article ofPolycarbonate Resin

In the same manner as the above (14), a molded article of polycarbonateresin of 60 mm×60 mm×3 mm in thickness was molded. Then, the moldedarticle of polycarbonate resin was immersed in methylene chloride (about400 g) at room temperature (25° C.) and was completely dissolved, toobtain a methylene chloride solution. About 50 g of the methylenechloride solution was taken, methylene chloride was removed underreduced pressure by means of an evaporator to obtain a residue. Theresidue was dissolved in deuterochloroform, and the solution wassubjected to measurement by ¹H-NMR method. From the signal intensity ofstructural units (a) and the signal intensities of other structuralunits in the obtained ¹H-NMR spectrum, the content [T] (wt %) of thestructural units (a) in the entire molded article was calculated.

The polycarbonate resins used in Examples and Comparative Examples areas follows.

(1) Polycarbonate Resin (a) (Reference Example 1): Preparation of PC(a1)(BPC Homopolymer, Melt Method)

To 37.60 kg (about 147 mol) of 2,2-bis(4-hydroxy-3-methylphenyl)propane(hereinafter sometimes referred to as “BPC”) (manufactured by HONSHUCHEMICAL INDUSTRY CO., LTD.) as a material dihydroxy compound and 32.20kg (about 150 mol) of diphenyl carbonate (DPC), an aqueous solution ofcesium carbonate was added so that cesium carbonate would be 2 μmol per1 mol of the dihydroxy compound to prepare a mixture. Then, the mixturewas charged into a first reactor having an internal volume of 200 Lequipped with a stirring machine, a heat medium jacket, a vacuum pumpand a reflux condenser.

Then, an operation of reducing the pressure in the first reactor to 1.33kPa (10 Torr) and then recovering it to the atmospheric pressure bynitrogen was repeatedly carried out five times, and then the interior inthe first reactor was replaced with nitrogen. After replacement withnitrogen, a heat medium at a temperature of 230° C. was passed throughthe heat medium jacket to gradually increase the internal temperature inthe first reactor thereby to dissolve the mixture. Then, the stirringmachine was rotated at 300 rpm, and the temperature in the heat mediumjacket was controlled to keep the internal temperature of the firstreactor at 220° C. Then, while phenol formed as a by-product by anoligomerization reaction of BPC and DPC conducted in the interior of thefirst reactor was distilled off, the pressure in the first reactor wasreduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) by the absolutepressure over a period of 40 minutes.

Then, the pressure in the first reactor was maintained at 13.3 kPa, andwhile phenol was further distilled off, an ester exchange reaction wascarried out for 80 minutes.

Further, the pressure in the system was recovered to 101.3 kPa by theabsolute pressure with nitrogen, and then the pressure was elevated to0.2 mPa by the gauge pressure, and by means of a transfer pipepreliminarily heated to at least 200° C., the oligomer in the firstreactor was pumped to a second reactor. The second reactor had aninternal volume of 200 L, was equipped with a stirring machine, a heatmedium jacket, a vacuum pump and a reflux condenser, and had theinternal pressure and the internal temperature controlled to theatmospheric pressure and 240° C.

Then, the oligomer pumped to the second reactor was stirred at 38 rpm,the internal temperature was raised by the heat medium jacket, and thepressure in the second reactor was reduced from 101.3 kPa to 13.3 kPa bythe absolute pressure over a period of 40 minutes. Then, thetemperature-raising was continued, and the internal pressure was reducedfrom 13.3 kPa to 399 Pa (3 Torr) by the absolute pressure further over aperiod of 40 minutes, and distilled phenol was removed out of thesystem. Further, the temperature raising was continued, and after theabsolute pressure in the second reactor reached 70 Pa (about 0.5 Torr),the pressure was maintained at 70 Pa, and a polycondensation reactionwas carried out. The final internal temperature in the second reactorwas 285° C. When the stirring machine of the second reactor achieved apreliminarily described predetermined stirring power, thepolycondensation reaction was completed.

Then, the pressure in the second reactor was recovered to 101.3 kPa bythe absolute pressure with nitrogen, and the pressure was elevated to0.2 mPa by the gauge pressure, and a polycarbonate resin was withdrawnfrom the bottom of the second reactor in the form of strands, which werepelletized by using a rotary cutter while cooling in a water tank. Theviscosity average molecular weight of the obtained polycarbonate resinwas 18,500. The melt viscosity was 2,361 Poise.

(Reference Example 2): Preparation of PC(a2) (BPC Homopolymer,Interfacial Method)

360 parts by weight of BPC (manufactured by HONSHU CHEMICAL INDUSTRYCO., LTD.) as the material dihydroxy compound, 585.1 parts by weight ofa 25 wt % sodium hydroxide (NaOH) aqueous solution and 1,721.5 parts byweight of water, in the presence of 0.41 part by weight of hydrosulfite,were dissolved at 40° C. and then cooled to 20° C. to obtain a BPCaqueous solution. This BPC aqueous solution in a rate of 8.87 kg/hour(the amount per one hour, the same applies hereinafter) and methylenechloride in a rate of 4.50 kg/hour were introduced into a 1.8 L glassfirst reactor equipped with a reflux condenser, a stirring machine and acoolant jacket, and were brought into contact with phosgene at roomtemperature separately supplied thereto in a rate of 0.672 kg/hour. Thereaction temperature at this time reached 35° C. Then, the reactionliquid/reaction gas mixture was introduced into a subsequent secondreactor (1.8 L) having the same shape as the first reactor by means ofan overflow tube attached to the reactor and reacted. Into the secondreactor, separately, p-t-butylphenol (8 wt % methylene chloridesolution) as a molecular weight adjusting agent was introduced in a rateof 0.097 kg/hour. Then, the reaction liquid/reaction gas was introducedinto an oligomerization tank (4.5 L) having the same shape as the firstreactor through an overflow tube attached to the second reactor. Intothe oligomerization tank, separately, a 2 wt % trimethylamine aqueoussolution as a catalyst was introduced in a rate of 0.020 kg/hour. Then,the oligomerized emulsion thus obtained was further introduced into aseparation tank (settler) having an internal volume of 5.4 L to separatean aqueous phase and an oil phase, thereby to obtain a methylenechloride solution of the oligomer.

2.60 kg of the above methylene chloride solution of the oligomer wascharged into a reaction tank having an internal volume of 6.8 L equippedwith a paddle blade, and 2.44 kg of methylene chloride for dilution wasadded, and further 0.278 kg of a 25 wt % sodium hydroxide aqueoussolution, 0.927 kg of water, 8.37 g of a 2 wt % triethylamine aqueoussolution and 25.8 g of p-t-butylphenol (8 wt % methylene chloridesolution) were added, followed by stirring at 10° C. to carry out apolycondensation reaction for 180 minutes.

3.12 kg of the polycondensation reaction liquid was charged into areaction tank having an internal volume of 5.4 L equipped with a paddleblade, and 2.54 kg of methylene chloride and 0.575 kg of water wereadded, followed by stirring for 15 minutes, and then stirring wasstopped, and an aqueous phase and an organic phase were separated. Tothe separated organic phase, 1.16 kg of 0.1 N hydrochloric acid wasadded, followed by stirring for 15 minutes, to extract triethylamine andan alkali component remaining in a small amount, and then stirring wasstopped, and an aqueous phase and an organic phase were separated.Further, to the separated organic phase, 1.16 kg of pure water wasadded, followed by stirring for 15 minutes, and then stirring wasstopped, and an aqueous phase and an organic phase was separated. Thisoperation was repeated three times. The obtained polycarbonate solutionwas fed into warm water of from 60 to 75° C. to powder the polycarbonateresin, followed by drying to obtain a powdery polycarbonate resin. Theviscosity average molecular weight of the obtained polycarbonate resinwas 9,500.

(Reference Example 3): Preparation of PC (a3) (Bis-OCZ Homopolymer, MeltMethod)

The same operation as in Reference Example 1 was carried out except that43.48 kg of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane (hereinaftersometimes referred to as “bis-OCZ”) (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) was used instead of BPC as the material dihydroxycompound, and the aqueous solution of cesium carbonate was added so thatcesium carbonate would be 5 μmol per 1 mol of the dihydroxy compound.The viscosity average molecular weight of the obtained polycarbonateresin was 10,200. The melt viscosity was 1,641 Poise.

(Reference Example 4): Preparation of PC(a4) (BPC/BPA (50/50 wt %)Copolymer, Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 1 except that 17.71 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) and bisphenol A (hereinafter sometimes referred toas “BPA”) (manufactured by Mitsubishi Chemical Corporation) were usedinstead of BPC as the material dihydroxy compounds. The viscosityaverage molecular weight of the obtained polycarbonate resin was 19,800.

(Reference Example 5): Preparation of PC(a5) (BPC/BPA (30/70 wt %)Copolymer, Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 1 except that 10.38 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) and 24.22 kg of BPA (manufactured by MitsubishiChemical Corporation) were used instead of BPC as the material dihydroxycompounds. The viscosity average molecular weight of the obtainedpolycarbonate resin was 20,300.

(Reference Example 6): Preparation of PC(a6) (BPC/BPA (10/90 wt %)Copolymer, Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 1 except that 3.39 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) and 30.47 kg of BPA (manufactured by MitsubishiChemical Corporation) were used instead of BPC as the material dihydroxycompounds. The viscosity average molecular weight of the obtainedpolycarbonate resin was 21,000.

(Reference Example 7): Preparation of PC(a7) (CDOBC/BPA (50/50 wt %)Copolymer, Melt Method)

The same operation as in Reference Example 1 was carried out except that20.62 kg (about 90 mol) of BPA and 20.62 kg (about 54 mol) of1,1-bis(4-hydroxy-3-methylphenyl)cyclododecane (hereinafter sometimesreferred to as “CDOBC”) (manufactured by Taoka Chemical Co., Ltd.) wereused as the material dihydroxy compounds, and the aqueous solution ofcesium carbonate was added so that cesium carbonate would be 1 μmol per1 mol of the dihydroxy compounds to prepare a mixture. Of the obtainedpolycarbonate resin, the viscosity average molecular weight was 11,700,and the pencil hardness was 2H.

(Reference Example 2-1): Preparation of PC (a2-1) (BPC Homopolymer,Mv=33,000, Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 1 except that the polycondensation reaction was completed whenthe stirring machine of the second reactor achieved a predeterminedstirring power (stirring power higher than in Reference Example 1). Ofthe obtained polycarbonate resin, the viscosity average molecular weightwas 33,000, and the melt viscosity was 18,195 Poise.

(Reference Example 2-2): Preparation of PC(a2-2) (Bis-OCZ Homopolymer,Mv=2,100, Melt Method)

To 43.48 kg (about 147 mol) of bis-OCZ (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) as the material dihydroxy compound and 32.20 kg(about 150 mol) of diphenyl carbonate (DPC), an aqueous solution ofcesium carbonate was added so that cesium carbonate would be 5 μmol per1 mol of the dihydroxy compound to be prepare a mixture. The mixture wascharged into a first reactor having an internal volume of 200 L equippedwith a stirring machine, a heat medium jacket, a vacuum pump and areflux condenser.

Then, an operation of reducing the pressure in the first reactor to 1.33kPa (10 Torr) and recovering it to the atmospheric pressure withnitrogen was repeatedly carried out five times, and the interior of thefirst reactor was replaced with nitrogen. After replacement withnitrogen, a heat medium at a temperature of 230° C. was passed throughthe heat medium jacket to gradually increase the internal temperature ofthe first reactor thereby to dissolve the mixture. Then, the stirringmachine was rotated at 300 rpm, and the temperature in the heat mediumjacket was controlled to maintain the internal temperature of the firstreactor at 220° C. Then, while phenol formed as a by-product by anoligomerization reaction of BPC and DPC carried out in the interior ofthe first reactor was distilled off, the pressure in the first reactorwas reduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) by theabsolute pressure over a period of 40 minutes.

Then, the pressure in first reactor was maintained at 13.3 kPa, andwhile phenol was further distilled off, an ester exchange reaction wascarried out for 80 minutes. Then, the polycarbonate resin was withdrawnfrom a valve at the bottom of the reactor. The viscosity averagemolecular weight of the obtained polycarbonate resin was 2,100.

(Reference Example 3-1): PC(a3-1)

100 parts by weight of Bis-OCZ as the material dihydroxy compound, 272.1parts by weight of a 25 wt % sodium hydroxide (NaOH) aqueous solutionand 411.3 parts by weight of water, in the presence of 0.339 part byweight of hydrosulfite, were dissolved at 60° C. and then cooled to roomtemperature to obtain a Bis-OCZ aqueous solution. This Bis-OCZ aqueoussolution in a rate of 8.87 kg/hour and methylene chloride in a rate of4.37 kg/hour were introduced into a 1.8 L glass first reactor equippedwith a reflux condenser, a stirring machine and a coolant jacket, andbrought into contact with phosgene at room temperature separatelysupplied thereto in a rate of 0.775 kg/hour. The reaction time at thistime reached 38° C. Then, the reaction liquid/reaction gas mixture wasintroduced into a subsequent second reactor (1.8 L) having the sameshape as the first reactor through an overflow tube attached to thereactor, and reacted. To the second reactor, separately, p-t-butylphenol(16 wt % methylene chloride solution) as a molecular weight adjustingagent was introduced at a rate of 0.037 kg/hour. Then, the reactionliquid/reaction gas mixture was introduced into an oligomerization tank(4.5 L) having the same shape as the first reactor through an overflowtube attached to the second reactor. To the oligomerization tank,separately, a 2 wt % trimethylamine aqueous solution as a catalyst wasintroduced at a rate of 0.016 kg/hour (0.00083 mol per 1 mol ofBis-OCZ). Then, the oligomerized emulsion thus obtained was furtherintroduced into a separation tank (settler) having an internal volume of5.4 L to separate an aqueous phase and an oil phase, thereby to obtain amethylene chloride solution of the oligomer.

2.44 kg of the above methylene chloride solution of the oligomer wascharged into a reaction tank having an internal volume of 6.8 L equippedwith a paddle blade, and 2.60 kg of methylene chloride for dilution wasadded, and further 0.245 kg of a 25 wt % sodium hydroxide aqueoussolution, 0.953 kg of water and 8.39 g of a 2 wt % triethylamine aqueoussolution were added, followed by stirring at 10° C. to carry out apolycondensation reaction for 180 minutes.

3.12 kg of the above polycondensation reaction liquid was charged into areaction tank having an internal volume of 5.4 L equipped with a paddleblade, and 2.54 kg of methylene chloride and 0.575 kg of water wereadded, followed by stirring for 15 minutes, and then stirring wasstopped to separate an aqueous phase and an organic phase. To theseparated organic phase, 1.16 kg of 0.1 N hydrochloric acid was added,followed by stirring for 15 minutes, to extract triethylamine and analkali component remaining in a small amount, and then stirring wasstopped to separate an aqueous phase and an organic phase. Further, tothe separated organic phase, 1.16 kg of pure water was added, followedby stirring for 15 minutes, and then stirring was stopped and an aqueousphase and an organic phase were separated. This operation was repeatedthree times. The obtained polycarbonate solution was fed into warm waterof from 60 to 75° C., to powder the polycarbonate resin, followed bydrying to obtain a powdery polycarbonate resin. Of the obtainedpolycarbonate resin, the viscosity average molecular weight was 49,900,and the melt viscosity was 127,200 poise.

(Reference Example 4-1): Preparation of PC(a-4-1): Preparation of BPCHomopolymer (Melt Method)

To 37.60 kg (about 147 mol) of 2,2-bis(4-hydroxy-3-methylphenyl)propane(hereinafter sometimes referred to as “BPC”) (manufactured by HONSHUCHEMICAL INDUSTRY CO., LTD.) as the material dihydroxy carbonate and32.20 kg (about 150 mol) of diphenyl carbonate (DPC), an aqueoussolution of cesium carbonate was added so that cesium carbonate would be2 μmol per 1 mol of the dihydroxy compound to prepare a mixture. Then,the mixture was charged into a first reactor having an internal capacityof 200 L equipped with a stirring machine, a heat medium jacket, avacuum pump and a reflux condenser.

Then, an operation of reducing the pressure in the first reactor to 1.33kPa (10 Torr) and then recovering it to the atmospheric pressure withnitrogen was repeatedly carried out five times, and the interior in thefirst reactor was replaced with nitrogen. After replacement withnitrogen, a heat medium at a temperature of 230° C. was passed throughthe heat medium jacket to gradually increase the internal temperature inthe first reactor to dissolve the mixture. Then, the stirring machinewas rotated at 300 rpm, and the temperature in the heat medium jacketwas controlled to maintain the internal temperature of the first reactorat 220° C. Then, while phenol formed as a by-product by anoligomerization reaction of BPC and DPC carried out in the interior ofthe first reactor was distilled off, the pressure in the first reactorwas reduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) over aperiod of 40 minutes.

Then, the pressure in the first reactor was maintained at 13.3 kPa, andwhile phenol was further distilled off, an ester exchange reaction wascarried out for 80 minutes.

Then, the pressure in the system was recovered to 101.3 kPa by theabsolute pressure with nitrogen, and then the pressure was elevated to0.2 mPa by the gauge pressure, and the oligomer in the first reactor waspumped to a second reactor by means of a transfer pipe preliminarilyheated to at least 200° C. The second reactor had an internal volume of200 L, was provided with a stirring machine, a heat medium jacket, avacuum pump and a reflux condenser, and had the internal pressure andthe internal temperature controlled to be the atmospheric pressure and240° C.

Then, the oligomer pumped to the second reactor was stirred at 38 rpm,the internal temperature was raised by the heat medium jacket, and thepressure in the second reactor was reduced from 101.3 kPa to 13.3 kPa bythe absolute pressure over a period of 40 minutes. Then, the temperatureraising was continued, and the internal pressure was reduced from 13.3kPa to 399 Pa (3 Torr) by the absolute pressure further over a period of40 minutes, and the distilled phenol was removed out of the system.Further, the temperature raising was continued, and after the absolutepressure in the second reactor reached 70 Pa (about 0.5 Torr), apressure of 70 Pa was maintained, and a polycondensation reaction wascarried out. The final internal temperature in the second reactor was285° C. When the stirring machine of the second reactor achieved apreliminarily determined stirring power, the polycondensation reactionwas completed.

Then, the pressure in the second reactor was recovered to 101.3 kPa bythe absolute pressure with nitrogen, and then the pressure was elevatedto 0.2 mPa by the gauge pressure, and the polycarbonate resin waswithdrawn from the bottom of the second reactor in the form of strands,which are pelletized by using a rotary cutter while cooling in a watertank. The viscosity average molecular weight of the obtainedpolycarbonate resin was 17,200.

The polycarbonate resin was evaluated in accordance with the aboveitems.

The results are shown in Table 1.

(Reference Example 4-2): Preparation of PC (a-4-2) (BPC Homopolymer,Melt Method)

The same operation as in Reference Example 1 was carried out except thatthe preliminarily determined stirring power of the stirring machine ofthe second reactor was changed. The viscosity average molecular weightof the obtained polycarbonate resin was 30,300. Further, thepolycarbonate resin was evaluated in the same manner as in ReferenceExample 1. The results are shown in Table 1.

(Reference Example 4-3): Preparation of PC(a-4-3) (BPC/BPA Copolymer,Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 5 except that the polycondensation reaction was completed whenthe stirring machine of the second reactor achieved a preliminarilydetermined stirring power (a stirring power higher than in ReferenceExample 5). The viscosity average molecular weight of the obtainedpolycarbonate resin was 25,200.

(Reference Example 4-4): Preparation of PC(a-4-4) (BPC/BPA Copolymer,Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 6 except that the polycondensation reaction was completed whenthe stirring machine of the second reactor achieved a preliminarilydetermined stirring power (a stirring power higher than in ReferenceExample 6). The viscosity average molecular weight of the obtainedpolycarbonate resin was 24,700.

(2) Polycarbonate Resin (b) (Reference Example 8): PC(b1) (BPAHomopolymer, Melt Method)

As PC(b1), a commercially available polycarbonate resin (manufactured byMitsubishi Engineering-Plastics Corporation, M7022J) comprising onlystructural units derived from BPA by the melt method was used. Theviscosity average molecular weight of PC(b1) was 20,600. The meltviscosity was 9,010 poise.

(Reference Example 3-2): PC(b3-1) (BPA Homopolymer, Melt Method)

As PC(b3-1), a commercially available polycarbonate resin (manufacturedby Mitsubishi Engineering-Plastics Corporation, M7027J) comprising onlystructural units derived from BPA by the melt method was used. Theviscosity average molecular weight of PC(b2) was 25,600, and the meltviscosity was 22,120 poise.

(Reference Example 3-3): Preparation of PC(b3-2)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 1 except that 3.4 kg of Bis-OCZ (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) and 30.9 kg of BPA (manufactured by MitsubishiChemical Corporation) were used instead of BPC as the material dihydroxycompounds. The viscosity average molecular weight of the obtainedpolycarbonate resin was 19,800.

(Reference Example 4-5): PC(b-4-1) (BPA Homopolymer, Melt Method)

As PC (b-4-1), a commercially available polycarbonate resin(manufactured by Mitsubishi Engineering-Plastics Corporation, M7022J)comprising only structural units derived from BPA by the melt method wasused. The viscosity average molecular weight of PC(b-4-1) was 20,000.Further, evaluation was carried out in the same manner as in ReferenceExample 1. The results are shown in Table 4-1.

Example 1

As the polycarbonate resin (a) and the polycarbonate resin (b), PC(a1)and PC(b1) in a ratio as identified in Table 1 were melt-kneaded in atwin screw extruder (LABOTEX 30HSS-32) manufactured by Japan SteelWorks, Ltd. having one vent port, extruded from the outlet of the twinscrew extruder in the form of strands, solidified by cooling with water,and pelletized by a rotary cutter to obtain a polycarbonate resincomposition. On that occasion, the barrel temperature of the twin screwextruder was 280° C., and the polycarbonate resin temperature at theoutlet of the twin screw extruder was 300° C. At the time ofmelt-kneading, the vent port of the twin screw extruder was connected toa vacuum pump, and the pressure at the vent port was controlled to be500 Pa.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the Charpy impact strength, theyellowness index (YI), the melt viscosity and the viscosity averagemolecular weight, in accordance with methods described in the aboveevaluation items. The results are shown in Table 1.

Further, the polycarbonate resin composition was molded into an extrudedarticle (sheet) by the above method, which was subjected to evaluationwith respect to the pencil hardness and the yellowness index (YI).

Examples 2 to 9

Polycarbonate resin compositions in Examples 2 to 9 were obtained in thesame manner as in Example 1 except that two types of polycarbonateresins as identified in Table 1 were employed.

The polycarbonate resin compositions were subjected to evaluation withrespect to the pencil hardness, the Charpy impact strength, theyellowness index (YI), the melt viscosity and the viscosity averagemolecular weight in accordance with methods as described in the aboveevaluation items. The results are shown in Table 1.

Further, the polycarbonate resin compositions in Examples 2 and 3 weremolded into extruded articles (sheets) by the above method, which weresubjected to evaluation with respect to the pencil hardness and theyellowness index (YI).

Example 10

Two types of polycarbonate resins as identified in Table 1 weredry-blended to obtain a polycarbonate resin composition.

The polycarbonate resin composition was evaluated with respect to thepencil hardness, the Charpy impact strength, the yellowness index (YI)and the viscosity average molecular weight in accordance with methods asdescribed in the above evaluation items.

The results are shown in Table 1.

Comparative Examples 1 to 5

The pencil hardness, the Charpy impact strength, the yellowness index(YI), the melt viscosity and the viscosity average molecular weight ofPC(a1) in Comparative Example 1, PC(b1) in Comparative Example 2, PC(a5)in Comparative Example 3, PC(a6) in Comparative Example 4 and PC(a3) inComparative Example 5 by themselves were evaluated. The results areshown in Table 1.

Further, the polycarbonate resin compositions in Comparative Examples 1to 4 were molded into extruded articles (sheets) by the above method,which were subjected to evaluation with respect to the pencil hardnessand the yellowness index (YI).

Comparative Example 6

A polycarbonate resin composition in Comparative Example 6 was obtainedin the same manner as in Example 1 except that two types ofpolycarbonate resins as identified in Table 1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the Charpy impact strength, theyellowness index (YI), the melt viscosity and the viscosity averagemolecular weight in accordance with methods as described in the aboveevaluation items.

Further, the polycarbonate resin composition was molded into an extrudedarticle (sheet) by the above method, which was subjected to evaluationwith respect to the pencil hardness and the yellowness index (YI). Theresults are shown in Table 1.

Comparative Example 7

A polycarbonate resin composition in Comparative Example 7 was obtainedin the same manner as in Example 1 except that PC(a1) and the BPCmonomer as identified in Table 1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the Charpy impact strength, theyellowness index (YI) and the melt viscosity in accordance with methodsas described in the above evaluation items. The results are shown inTable 1.

TABLE 1 Polycarbonate resin (a) Polycarbonate resin (b) Blending Charpyimpact Blending amount strength amount Type (wt %) Hardness (kJ/m²) Type(wt %) Hardness Ex. 1 BPC homopolymer (melt method) 30 2H 6 BPAhomopolymer (melt method) 70 2B Ex. 2 BPC homopolymer (melt method) 202H 6 BPA homopolymer (melt method) 80 2B Ex. 3 BPC homopolymer (meltmethod) 10 2H 6 BPA homopolymer (melt method) 90 2B Ex. 4 BPChomopolymer (interfacial method) 20 2H 5 BPA homopolymer (melt method)80 2B Ex. 5 Bis-OCZ homopolymer (melt method) 30 3H 4 BPA homopolymer(melt method) 70 2B Ex. 6 Bis-OCZ homopolymer (melt method) 20 3H 4 BPAhomopolymer (melt method) 80 2B Ex. 7 Bis-OCZ homopolymer (melt method)10 3H 4 BPA homopolymer (melt method) 90 2B Ex. 8 BPC/BPA (50/50 wt %)copolymer 20 H 7 BPA homopolymer (melt method) 80 2B Ex. 9 BPChomopolymer (melt method) 20 2H 6 BPA homopolymer (melt method) 80 2BEx. 10 CDOBC/BPA (50/50 wt %) copolymer 30 H 5 BPA homopolymer (meltmethod) 70 2B Comp. BPC homopolymer (melt method) 100 2H — — — — Ex. 1Comp. — — — — BPA homopolymer (melt method) 100 2B Ex. 2 Comp. BPC/BPA(30/70 wt %) copolymer 100 F — — — — Ex. 3 Comp. BPC/BPA (10/90 wt %)copolymer 100 B — — — — Ex. 4 Comp. Bis-OCZ homopolymer (melt method)100 3H — — — — Ex. 5 Comp. BPC homopolymer (melt method) 50 2H 6 BPAhomopolymer (melt method) 50 2B Ex. 6 Comp. BPC monomer (*) 0.1 — — BPAhomopolymer (melt method) 99.9 2B Ex. 7 Blend ratio (wt %) of dihydroxycompound Polycarbonate resin composition BPC Bis-OCZ CDOBC BPAproduction method Ex. 1 30 — — 70 Melt-kneading Ex. 2 20 — — 80Melt-kneading Ex. 3 10 — — 90 Melt-kneading Ex. 4 20 — — 80Melt-kneading Ex. 5 — 30 — 70 Melt-kneading Ex. 6 — 20 — 80Melt-kneading Ex. 7 — 10 — 90 Melt-kneading Ex. 8 10 — — 90Melt-kneading Ex. 9 20 — — 80 Dry-blending Ex. 10 — — 30 70Melt-kneading Comp. 100 — — — — Ex. 1 Comp. — — — 100 — Ex. 2 Comp. 30 —— 70 — Ex. 3 Comp. 10 — — 90 — Ex. 4 Comp. — 100 — — — Ex. 5 Comp. 50 —— 50 Melt-kneading Ex. 6 Comp. 0.1 — — 99.9 Melt-kneading Ex. 7Polycarbonate resin composition Charpy impact Melt Polycarbonate resinsheet Pencil Comparison of pencil strength viscosity Mv(a)/ Pencilhardness hardness with PC(b) (kJ/m²) YI (poise) Mv(b) hardness YI Ex. 1H Four ranks up (2B→H) 8 2.8 5,980 0.90 H 0.87 Ex. 2 F Three ranks up(2B→F) 11 2.5 6,920 0.90 H 0.86 Ex. 3 F Three ranks up (2B→F) 14 2.37,850 0.90 F 0.86 Ex. 4 F Three ranks up (2B→F) 8 2.9 5,160 0.46 — — Ex.5 H Four ranks up (2B→H) 8 2.0 5,140 0.50 — — Ex. 6 F Three ranks up(2B→F) 9 2.0 6,800 0.50 — — Ex. 7 HB Two ranks up (2B→HB) 12 1.9 7,9300.50 — — Ex. 8 HB Two ranks up (2B→HB) 13 2.5 — 0.96 — — Ex. 9 F Threeranks up (2B→F) 10 2.3 — 0.90 — — Ex. 10 F Three ranks up (2B→F) 9 2.5 —0.57 — — Comp. 2H — 6 4.0 2,360 — 2H 1.05 Ex. 1 Comp. 2B — 72 1.9 9,010— B 0.88 Ex. 2 Comp. F — 8 2.9 — — F 0.99 Ex. 3 Comp. B — 14 2.4 — — HB0.95 Ex. 4 Comp. 3H — 4 3.6 1,640 — — — Ex. 5 Comp. H Four ranks up(2B→H) 7 3.3 4,200 0.90 2H 0.95 Ex. 6 Comp. 2B — 70 1.9 8,610 — — — Ex.7 (*): As polycarbonate resin (a) in Comparative Example 7, a monomerwas used, not a polycarbonate resin.

In Example 1 and Comparative Example 3, as the blend ratio of thedihydroxy compound is the same, the content of structural units derivedfrom each dihydroxy compound is estimated to be the same. Nevertheless,Example 1 ranks higher in the pencil hardness as specified by ISO 15184than Comparative Example 3. Further, with respect to the yellownessindex (YI), Example 1 is superior to Comparative Example 3.

Likewise, in Example 3 and Comparative Example 4, in which the contentof structural units derived from each dihydroxy compound is estimated tobe the same, it is found that Example 3 is remarkably superior in thepencil hardness to Comparative Example 4. Further, by comparison betweenExample 1 and Comparative Example 6, it is found that if the weightratio of the polycarbonate resin (a) to the polycarbonate resin (b)exceeds a specific range, the Charpy impact strength and the yellownessindex (YI) are deteriorated.

Example 2-1

As the polycarbonate resin (a) and the polycarbonate resin (b), BPChomopolymer and PC(b1) in a ratio as identified in Table 2-1 weremelt-kneaded in a twin screw extruder (LABOTEX 30HSS-32) manufactured byJapan Steel Works, Ltd. having one vent port, extruded from the outletof the twin screw extruder in the form of strands, solidified by coolingwith water, and pelletized by a rotary cutter to obtain a polycarbonateresin composition. On that occasion, the barrel temperature of the twinscrew extruder was 280° C., and the polycarbonate resin temperature atthe outlet of the twin screw extruder was 300° C. At the time ofmelt-kneading, the vent port of the twin screw extruder was connected toa vacuum pump, and the pressure at the vent port was controlled to be500 Pa.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the melt viscosity, the Charpy impactstrength and the yellowness index (YI), in accordance with methodsdescribed in the above evaluation items. Further, the pencil hardnessand the yellowness index (YI) of the polycarbonate resin sheet wereevaluated in accordance with methods as described in the aboveevaluation items. The results are shown in Table 2-1.

Examples 2-2 to 2-5, 2-7 and 2-8

Polycarbonate resin compositions in Examples 2-2 to 2-5, 2-7 and 2-8were obtained in the same manner as in Example 2-1 except that two typesof polycarbonate resins as identified in Table 2-1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the melt viscosity, the Charpy impactstrength and the yellowness index (YI) in accordance with methods asdescribed in the above evaluation items. Further, in Example 2-2, thepencil hardness and the yellowness index (YI) of the polycarbonate resinsheet were evaluated in accordance with methods as described in theabove evaluation items. The results are shown in Table 2-1.

Example 2-6

Two types of polycarbonate resins as identified in Table 2-1 weredry-blended to obtain a polycarbonate resin composition. Thepolycarbonate resin composition was subjected to evaluation with respectto the pencil hardness, the Charpy impact strength, the yellowness index(YI) and the viscosity average molecular weight in accordance withmethods as described in the above evaluation items. The results areshown in Table 2-1.

Comparative Examples 2-1, 2-3 and 2-7

Polycarbonate resin compositions in Comparative Examples 2-1, 2-3 and2-7 were obtained in the same manner as in Example 2-1 except that twotypes of polycarbonate resins as identified in Table 2-1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the melt viscosity, the Charpy impactstrength and the yellowness index (YI) in accordance with methods asdescribed in the above evaluation items. Further, with respect to thepolycarbonate resin compositions in Comparative Examples 2-1 and 2-7,the pencil hardness and the yellowness index (YI) of the polycarbonateresin sheet were evaluated in accordance with methods as described inthe above evaluation items. The results are shown in Table 2-1.

Comparative Examples 2-2, 2-4, 2-5 and 2-6

The pencil hardness, the melt viscosity, the Charpy impact strength andthe yellowness index (YI) of PC(a5) in Comparative Example 2-2, PC(a6)in Comparative Example 2-4, PC(a1) in Comparative Example 2-5 and PC(b1)in Comparative Example 2-6 by themselves were evaluated. Further, thepencil hardness and the yellowness index (YI) of the polycarbonate resinsheet were evaluated in accordance with methods as described in theabove evaluation items. The results are shown in Table 2-1.

Comparative Example 2-8

A polycarbonate resin composition in Comparative Example 2-8 wasobtained in the same manner as in Example 2-1 except that PC(b1) and theBPC monomer as identified in Table 2-1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the pencil hardness, the melt viscosity, the Charpy impactstrength and the yellowness index (YI) in accordance with methods asdescribed in the above evaluation items. The results are shown in Table2-1.

TABLE 2-1 Polycarbonate resin (a) Polycarbonate resin (b) BlendingPencil Blending Type amount (wt %) Mv(a) hardness Type amount (wt %)Mv(b) Ex. 2-1 BPC homopolymer (melt method) 30 18,500 2H BPA homopolymer(melt method) 70 20,600 Ex. 2-2 BPC homopolymer (melt method) 10 18,5002H BPA homopolymer (melt method) 90 20,600 Ex. 2-3 Bis-OCZ homopolymer(melt method) 30 10,200 3H BPA homopolymer (melt method) 70 20,600 Ex.2-4 BPC/BPA (50/50 wt %) copolymer 20 19,800 H BPA homopolymer (meltmethod) 80 20,600 Ex. 2-5 BPC homopolymer (interfacial 20 9,500 2H BPAhomopolymer (melt method) 80 20,600 method) Ex. 2-6 BPC homopolymer(melt method) 20 18,500 2H BPA homopolymer (melt method) 80 20,600 Ex.2-7 Bis-OCZ homopolymer (melt method) 20 2,100 3H BPA homopolymer (meltmethod) 80 20,600 Ex. 2-8 CDOBC/BPA (50/50 wt %) copolymer 30 H 5 BPAhomopolymer (melt method) 70 2B Comp. BPC homopolymer (melt method) 3033,000 2H BPA homopolymer (melt method) 70 20,600 Ex. 2-1 Comp. BPC/BPA(30/70 wt %) copolymer 100 20,300 F — — — Ex. 2-2 Comp. BPC homopolymer(melt method) 10 33,000 2H BPA homopolymer (melt method)- 90 20,600 Ex.2-3 Comp. BPC/BPA (10/90 wt %) copolymer 100 21,000 B — — — Ex. 2-4Comp. BPC homopolymer (melt method) 100 18,500 — — — — Ex. 2-5 Comp. — —— — BPA homopolymer (melt method) 100 20,600 Ex. 2-6 Comp. BPChomopolymer (melt method) 50 18,500 2H BPA homopolymer (melt method) 5020,600 Ex. 2-7 Comp. BPC monomer (*) 0.1 256 — BPA homopolymer (meltmethod) 99.9 20,600 Ex. 2-8 Blend ratio (wt %) Polycarbonate resincomposition Polycarbonate resin of dihydroxy compound PolycarbonateCharpy impact Melt sheet Bis- resin composition Mv(a)/ Pencil strengthviscosity Pencil BPC OCZ CDOBC BPA production method Mv(b) hardness(kJ/m²) YI (poise) hardness YI Ex. 2-1 30 — — 70 Melt-kneading 0.90 H 82.8 5,980 H 0.87 Ex. 2-2 10 — — 90 Melt-kneading 0.90 F 14 2.3 7,850 F0.86 Ex. 2-3 — 30 — 70 Melt-kneading 0.50 H 8 2.0 5,140 — — Ex. 2-4 10 —— 90 Melt-kneading 0.96 HB 13 2.5 — — — Ex. 2-5 20 — — 80 Melt-kneading0.46 F 8 2.9 5,160 — — Ex. 2-6 20 — — 80 Dry-blending 0.90 F 10 2.3 — —— Ex. 2-7 20 — — 80 Melt-kneading 0.10 F 6 1.9 2,546 — — Ex. 2-8 — — 3070 Melt-kneading 0.57 F 9 2.5 — — — Comp. 30 — — 70 Melt-kneading 1.60 F10 3.3 11,140 F 0.91 Ex. 2-1 Comp. 30 — — 70 — — F 8 2.9 — F 0.99 Ex.2-2 Comp. 10 — — 90 Melt-kneading 1.60 HB 12 2.8 9,420 Ex. 2-3 Comp. 10— — 90 — — B 14 2.4 — HB 0.95 Ex. 2-4 Comp. 100 — — — — — 2H 6 4.0 2,3602H 1.05 Ex. 2-5 Comp. — — — 100 — — 2B 72 1.9 9,010 B 0.88 Ex. 2-6 Comp.50 — — 50 Melt-kneading 0.90 H 7 3.3 4,200 2H 0.95 Ex. 2-7 Comp. 0.1 — —99.9 Melt-kneading 0.01 2B 70 1.9 8,610 — — Ex. 2-8 (*): Aspolycarbonate resin (a) in Comparative Example 8, a monomer was used,not a polycarbonate resin.

In Example 2-1 and Comparative Example 2-2, as the blend ratio of thedihydroxy compound is the same, the content of structural units derivedfrom each dihydroxy compound is estimated to be the same. Nevertheless,Example 2-1 ranks higher in the pencil hardness as specified by ISO15184 than Comparative Example 2-2. Further, with respect to theyellowness index (YI), it is found that Example 2-1 is superior toComparative Example 2-2.

Likewise, in Example 2-2 and Comparative Example 2-4, in which thecontent of structural units derived from each dihydroxy compound isestimated to be the same, it is found that Example 2-2 is remarkablysuperior in the pencil hardness to Comparative Example 2-4. Further, bycomparison between Example 2-1 and Comparative Example 2-1, and betweenExample 2-2 and Comparative Example 2-3, it is found that if the ratioof the viscosity average molecular weight of the polycarbonate resin (a)to the viscosity average molecular weight of the polycarbonate resin (b)does not satisfy a specific range, the pencil hardness is decreased, andthe yellowness index (YI) is remarkably deteriorated. Further, bycomparison among Example 2-1, Example 2-2 and Comparative Example 2-7,it is found that if the weight ratio of the polycarbonate resin (a) tothe polycarbonate resin (b) exceeds a specific range, the Charpy impactstrength and the yellowness index (YI) are remarkably deteriorated.

Example 3-1

As the polycarbonate resin (a) and the polycarbonate resin (b), PC(a1)and PC(b1) in a ratio as identified in Table 1 were melt-kneaded in atwin screw extruder (LABOTEX 30HSS-32) manufactured by Japan SteelWorks, Ltd. having one vent port, extruded from the outlet of the twinscrew extruder in the form of strands, solidified by cooling with water,and pelletized by a rotary cutter to obtain a polycarbonate resincomposition. On that occasion, the barrel temperature of the twin screwextruder was 280° C., and the polycarbonate resin temperature at theoutlet of the twin screw extruder was 300° C. At the time ofmelt-kneading, the vent port of the twin screw extruder was connected toa vacuum pump, and the pressure at the vent port was controlled to be500 Pa.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the Charpy impact strength and the yellowness index (YI), in accordancewith methods as described in the above evaluation items. The results areshown in Table 3-1.

Further, the polycarbonate resin composition was molded into an extrudedarticle (sheet) by the above method, which was subjected to evaluationwith respect to the pencil hardness and the yellowness index (YI). Theresults are shown in Table 3-1.

Examples 3-2 to 3-4 and 3-6

Polycarbonate resin compositions in Examples 3-2 to 3-4 and 3-6 wereobtained in the same manner as in Example 3-1 except that two types ofpolycarbonate resins as identified in Table 3-1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the Charpy impact strength and the yellowness index (YI) in accordancewith methods as described in the above evaluation items. The results areshown in Table 3-1.

Further, the polycarbonate resin composition in Example 3-3 was moldedinto an extruded article (sheet) by the above method, which wassubjected to evaluation with respect to the pencil hardness and theyellowness index (YI). The results are shown in Table 3-1.

Example 3-5

As the polycarbonate resin (a) and the polycarbonate resin (b), pelletsof PC(a1) and pellets of PC(b1) in a ratio as identified in Table 3-1were dry-blended to obtain a polycarbonate resin composition in Example3-5.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the Charpy impact strength and the yellowness index (YI) in accordancewith methods as described in the above evaluation items. The results areshown in Table 3-1.

Further, the polycarbonate resin composition was molded into an extrudedarticle (sheet) by the above method, which was subjected to evaluationwith respect to the pencil hardness and the yellowness index (YI). Theresults are shown in Table 3-1.

Comparative Examples 3-1 to 3-4

Polycarbonate resin compositions in Comparative Examples 3-1 to 3-4 wereobtained in the same manner as in Example 3-1 except that two types ofpolycarbonate resins as identified in Table 3-1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the Charpy impact strength and the yellowness index (YI) in accordancewith methods as described in the above evaluation items. The results areshown in Table 3-1.

Further, the polycarbonate resin composition in Comparative Example 3-1was molded into an extruded article (sheet) by the above method, whichwas subjected to evaluation with respect to the pencil hardness and theyellowness index (YI). The results are shown in Table 3-1.

Comparative Examples 3-5 to 3-8

The surface hardness, the glass transition temperature (Tg), the Charpyimpact strength and the yellowness index (YI) of PC(b1) in ComparativeExample 3-5, PC(a1) in Comparative Example 3-6, PC(a6) in ComparativeExample 3-7 and PC(b3-2) in Comparative Example 3-8 by themselves wereevaluated, and the results are shown in Table 3-1.

Further, each of the polycarbonate resin compositions in ComparativeExamples 3-5 to 3-7 was molded into an extruded article (sheet) by theabove method, which was subjected to evaluation with respect to thepencil hardness and the yellowness index (YI). The results are shown inTable 3-1.

TABLE 3-1 Polycarbonate resin (a) Glass Blending transition amount MeltPencil Type temperature (° C.) (wt %) Mv viscosity hardness Ex. 3-1PC(a1) BPC homopolymer (melt method) 119 10 18,500 2,361 2H Ex. 3-2PC(a3) Bis-OCZ homopolymer (melt method) 132 10 10,200 1,641 3H Ex. 3-3PC(a1) BPC homopolymer (melt method) 119 20 18,500 2,361 2H Ex. 3-4PC(a2-1) BPC homopolymer (melt method) 122 20 33,000 18,195 2H Ex. 3-5PC(a1) BPC homopolymer (melt method) 119 20 18,500 2,361 2H Ex. 3-6PC(a7) CDOBC/BPA (50/50 wt %) copolymer 161 30 11,700 — 2H Comp. PC(a1)BPC homopolymer (melt method) 119 50 18,500 2,361 2H Ex. 3-1 Comp.PC(a2-1) BPC homopolymer (melt method) 122 20 33,000 18,195 2H Ex. 3-2Comp. PC(a3) Bis-OCZ homopolymer (melt method) 132 50 10,200 1,641 3HEx. 3-3 Comp. PC(a3-2) Bis-OCZ homopolymer (interfacial 138 20 49,900127,200 3H Ex. 3-4 method) Comp. — — — — — — — Ex. 3-5 Comp. PC(a1) BPChomopolymer (melt method) 119 20 18,500 2,361 2H Ex. 3-6 Comp. — — — — —— — Ex. 3-7 Comp. — — — — — — — Ex. 3-8 Polycarbonate resin (b) Glasstransition Blending Melt Pencil Type temperature (° C.) amount (wt %) Mvviscosity hardness Ex. 3-1 PC(b1) BPA homopolymer (melt method) 145 9020,600 9,010 2B Ex. 3-2 PC(b1) BPA homopolymer (melt method) 145 9020,600 9,010 2B Ex. 3-3 PC(b3-1) BPA homopolymer (melt method) 147 8025,600 22,120 2B Ex. 3-4 PC(b3-1) BPA homopolymer (melt method) 147 8025,600 22,120 2B Ex. 3-5 PC(b1) BPA homopolymer (melt method) 145 8020,600 22,120 2B Ex. 3-6 PC(b1) BPA homopolymer (melt method) 145 8020,600 22,120 2B Comp. PC(b1) BPA homopolymer (melt method) 145 8020,600 9,010 2B Ex. 3-1 Comp. PC(b1) BPA homopolymer (melt method) 14580 20,600 — 2B Ex. 3-2 Comp. PC(b1) BPA homopolymer (melt method) 145 5020,600 9,010 2B Ex. 3-3 Comp. PC(b1) BPA homopolymer (melt method) 14550 20,600 9,010 2B Ex. 3-4 Comp. PC(b1) BPA homopolymer (melt method)145 100 20,600 9,010 2B Ex. 3-5 Comp. — — — — — — — Ex. 3-6 Comp. PC(a6)BPA/BPC copolymer (melt method) 140 100 21,000 — B Ex. 3-7 Comp.PC(b3-2) BPA/Bis-OCZ copolymer (melt 143 100 19,800 — B Ex. 3-8 method)Polycarbonate resin composition Pencil Monomer unit (wt %) hardness onCharpy impact Polycarbonate sheet Bis- the surface of Tg strength YIComparison of pencil Pencil Thickness BPC OCZ CDOBC BPA molded article(° C.) (kJ/m²) (—) hardness with PC(b) hardness (μm) YI Ex. 3-1 10 — —90 F 142 14 2.3 Three ranks up (2B→F) F 240 0.86 Ex. 3-2 — 10 — 90 HB144 12 1.9 Two ranks up (2B→HB) — — — Ex. 3-3 20 — — 80 F 142 12 2.5Three ranks up (2B→F) F 240 0.86 Ex. 3-4 20 — — 80 F 143 14 2.7 Threeranks up (2B→F) Ex. 3-5 20 — — 80 F — 11 2.3 Three ranks up (2B→F) H 2400.86 Ex. 3-6 — — 15 85 F 149 9 2.5 Three ranks up (2B→F) — — — Com-p. 50— — 50 H 131 7 3.3 Four ranks up (2B→H) 2H 240 0.95 Ex.3-1 Co-mp. 20 — —80 F 140 11 3.0 Three ranks up (2B→F) — — — Ex. 3-2 Comp. — 50 — 50 2H137 5 1.9 Five ranks up (2B→2H) — — — Ex. 3-3 Comp. — 20 — 80 F 146 113.8 Three ranks up (2B→F) — — — Ex. 3-4 Comp. — — — 100 2B 145 72 1.9 —B 240 0.88 Ex. 3-5 Comp. 100 — — 2H 119 6 4.0 — 2H 240 1.05 Ex. 3-6Comp. 10 — — 90 B 140 14 2.4 — HB 240 0.95 Ex. 3-7 Comp. — 10 — 90 B 14312 2.3 — — — — Ex. 3-8

In Example 3-1 and Comparative Example 3-7, as the blend ratio of thedihydroxy compound is the same, the content of structural units derivedfrom each dihydroxy compound is estimated to be the same. Nevertheless,it is found that Example 3-1 ranks higher in the pencil hardness asspecified by ISO 15184 by two ranks than Comparative Example 3-7.Further, with respect to the yellowness index (YI), Example 3-1 issuperior to Comparative Example 3-7. Likewise, with respect to Example3-2 and Comparative Example 3-8, in which the content of structuralunits derived from each dihydroxy compound is estimated to be the same,Example 3-2 is remarkably superior in the pencil hardness to ComparativeExample 3-8. Further, by comparison between Example 3-1 and ComparativeExample 3-1 and between Example 3-2 and Comparative Example 3-3, it isfound that if the weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b) exceeds a specific range, the glass transitiontemperature (Tg), the Charpy impact strength and the yellowness index(YI) are remarkably deteriorated. Further, by comparison between Example3-3 and Comparative Example 3-2 and between Example 3-4 and ComparativeExample 3-4, it is found that if the melt viscosity of the polycarbonateresin (a) and the melt viscosity of the polycarbonate resin (b) do notsatisfy a specific range, the Charpy impact strength is decreased, andthe yellowness index (YI) is remarkably deteriorated.

TABLE 4-1 Blend ratio (wt %) Intrinsic of dihydroxy viscosity PencilAbbreviated name compound Mv [η] hardness Reference BPC homopolymer BPC(100) 17,200 0.4 2H Ex. 4-1 (a4-1) Reference BPC homopolymer BPC (100)18,500 0.43 2H Ex. 1 (a1) Reference BPC homopolymer BPC (100) 30,3000.69 2H Ex. 4-2 (a4-2) Reference BisOC-Z BisOC-Z (100) 10,200 0.23 3HEx. 3 homopolymer (a3) Reference BPC/BPA copolymer BPC/BPA 25,200 0.55 FEx. 4-3 (a4-3) (30/70) Reference BPC/BPA copolymer BPC/BPA 24,700 0.55 BEx. 4-4 (a4-4) (10/90) Reference BPA homopolymer BPA (100) 20,000 0.462B Ex. 4-1 (b4-1) Reference BPA homopolymer BPA (100) 20,600 0.47 2B Ex.8 (b1) Reference BPA homopolymer BPA (100) 25,600 0.56 2B Ex. 3-2 (b3-1)

Example 4-1

As the polycarbonate resin (a) and the polycarbonate resin (b),PC(a-4-1) and PC(b-4-1) in a ratio as identified in Table 4-2 weremelt-kneaded in a twin screw extruder (LABOTEX 30HSS-32) manufactured byJapan Steel Works, Ltd. having one vent port, extruded from the outletof the twin screw extruder in the form of strands, solidified by coolingwith water, and pelletized by a rotary cutter to obtain a molded articleof polycarbonate resin. On that occasion, the barrel temperature of thetwin screw extruder was 280° C., and the polycarbonate resin temperatureat the outlet of the twin screw extruder was 300° C. At the time ofmelt-kneading, the vent port of the twin screw extruder was connected toa vacuum pump, and the pressure at the vent port was controlled to be500 Pa.

The molded article of polycarbonate resin was subjected to evaluationwith respect to the surface hardness, the Charpy impact strength, theyellowness index (YI), the content of structural units (a) on thesurface of the molded article of polycarbonate resin and the content ofstructural units (a) in the entire molded article of polycarbonate resinin accordance with methods as described in the above evaluation items.

The results are shown in Table 4-2. In Example 4-1, the structural units(a) are structural units derived from BPC.

Examples 4-2 to 4-4

Molded articles of polycarbonate resin in Examples 4-2 to 4-4 wereobtained in the same manner as in Example 4-1 except that two types ofpolycarbonate resins as identified in Table 4-2 were employed. Further,they were subjected to evaluation in the same manner as in Example 4-1.The results are shown in Table 4-2. In Examples 4-2 and 4-3, thestructural units (a) are structural units derived from BPC, and inExample 4-4, the structural units (a) are structural units derived fromBis-OCZ.

Comparative Examples 4-1 to 4-4

Molded articles of polycarbonate resin in Comparative Examples 4-1 to4-4 were obtained in the same manner as in Example 4-1 except that twotypes of polycarbonate resins as identified in Table 4-2 were employed.Further, they were subjected to evaluation in the same manner as inExample 4-1. The results are shown in Table 4-2. In Comparative Examples4-1 and 4-4, the structural units (a) are structural units derived fromBPC.

Comparative Examples 4-5 to 4-8

As identified in Table 4-2, as the polycarbonate resin, PC(a1) inComparative Example 4-5, PC(b1) in Comparative Example 4-6, PC(a-4-3) inComparative Example 4-7 and PC(a-4-4) in Comparative Example 4-8 wereused by themselves to obtain molded articles of polycarbonate resin inComparative Examples 4-5 to 4-8. Further, they were subjected toevaluation in the same manner as in Example 4-1. The results are shownin Table 4-2. In Comparative Examples 4-5, 4-7 and 4-8, the structuralunits (a) are structural units derived from BPC, and in ComparativeExample 4-6, the structural units (a) are structural units derived fromBPA.

TABLE 4-2 Polycarbonate resin (a) Polycarbonate resin (b) Blendingamount Blending amount Type wt % Type wt % Ex. 4-1 BPC homopolymer 20BPA homopolymer 80 (a4-1) (b4-1) Ex. 4-2 BPC homopolymer 10 BPAhomopolymer 90 (a1) (b1) Ex. 4-3 BPC homopolymer 10 BPA homopolymer 90(a1) (b3-1) Ex. 4-4 BisOC-Z 20 BPA homopolymer 10 homopolymer (a3) (b1)Comp. BPC homopolymer 50 BPA homopolymer 50 Ex. 4-1 (a1) (b1) Comp. BPChomopolymer 20 BPA homopolymer 80 Ex. 4-2 (a4-2) (b4-1) Comp. BPChomopolymer 10 BPA homopolymer 90 Ex. 4-3 (a4-2) (b1) Comp. BPChomopolymer 10 BPA homopolymer 80 Ex. 4-4 (a4-2) (b3-1) Comp. BPChomopolymer 100 — — Ex. 4-5 (a1) Comp. — — BPA homopolymer 100 Ex. 4-6(b1) Comp. BPA/BPC copolymer 70/30 — — Ex. 4-7 (a4-3) Comp. BPA/BPCcopolymer 90/10 — — Ex. 4-8 (a4-4) Molded article of polycarbonate resinContent of Structural units (a) structural units Content of structuralcontent ratio between Pencil hardness on Charpy (a) on the surface units(a) in the entire surface layer/the entire the surface of impactStructural of molded article molded article [S]/[T] molded articlestrength units (a) wt % wt % — — kJ/m² Ex. 4-1 BPC 23 20 1.15 F 11 Ex.4-2 BPC 11 10 1.1 F 14 Ex. 4-3 BPC 10.5 10 1.05 HB 17 Ex. 4-4 BisOC-Z 2220 1.1 F 9 Comp. BPC 49 50 0.98 H 7 Ex. 4-1 Comp. BPC 20 20 1.0 HB 11Ex. 4-2 Comp. BPC 10 10 1.0 HB 14 Ex. 4-3 Comp. BPC 10 10 1.0 B 10 Ex.4-4 Comp. BPC 100 100 1.0 2H 6 Ex. 4-5 Comp. — 100 100 1.0 2B 72 Ex. 4-6Comp. BPC 30 30 1.0 F 8 Ex. 4-7 Comp. BPC 10 10 1.0 B 14 Ex. 4-8

By comparison between Example 4-1 and Comparative Example 4-2, althoughthe content of structural units (a) (structural units derived from BPC)in the entire molded article of polycarbonate resin is the same, inExample 4-1, the content of the structural units (a) on the surface ofthe molded article of polycarbonate resin is high, and the pencilhardness as specified by ISO 15184 in Example 4-1 is higher than thepencil hardness in Comparative Example 4-2.

Likewise, by comparison among Example 4-2, Comparative Example 4-3 andComparative Example 4-8, although the content of structural units (a)(structural units derived from BPC) in the entire molded article ofpolycarbonate resin is the same, in Example 4-2, the content of thestructural units (a) (structural units derived from BPC) on the surfaceof the molded article of polycarbonate resin is high, and the pencilhardness as specified by ISO 15184 is high, as compared with ComparativeExamples 4-3 and 4-8.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to obtain apolycarbonate resin composition and a molded article, which have aremarkably improved surface hardness of the polycarbonate resincomposition comprising a relatively low general purpose aromaticpolycarbonate resin as the main component, and which have hightransparency, favorable color, and well-balanced impact strength andmoldability, and the present invention is applicable particularly toapplications for which the surface hardness is required, such aselectric/electronic equipment fields such as cellular phones andpersonal computers, automobile fields such as headlamp lenses andwindows for vehicles, and building material fields such as illuminationand exterior.

This application is a continuation of PCT Application No.PCT/JP2011/058326, filed on Mar. 31, 2011, which is based upon andclaims the benefit of priority from Japanese Patent Application No.2010-083181 filed on Mar. 31, 2010, Japanese Patent Application No.2010-262053 filed on Nov. 25, 2010, Japanese Patent Application No.2010-262054 filed on Nov. 25, 2010, Japanese Patent Application No.2010-262057 filed on Nov. 25, 2010, Japanese Patent Application No.2011-018523 filed on Jan. 31, 2011, Japanese Patent Application No.2011-018524 filed on Jan. 31, 2011, Japanese Patent Application No.2011-018527 filed on Jan. 31, 2011, Japanese Patent Application No.2011-047877 filed on Mar. 4, 2011 and Japanese Patent Application No.2011-076450 filed on Mar. 30, 2011. The contents of those applicationsare incorporated herein by reference in their entireties.

What is claimed is:
 1. A polycarbonate resin composition comprising atleast a polycarbonate resin (a) and a polycarbonate resin (b) havingstructural units different from the polycarbonate resin (a), wherein thepolycarbonate resin (b) has bis-phenol A structural units, whichsatisfies the following requirements: (i) the pencil hardness of thepolycarbonate resin (a) as specified by ISO 15184 is higher than thepencil hardness of the polycarbonate resin (b) as specified by ISO15184; (ii) the weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b) is from 10:90 to 30:70; (iii) the pencilhardness of the polycarbonate resin composition as specified by ISO15184 is higher by at least two ranks than the pencil hardness of thepolycarbonate resin (b) as specified by ISO 15184; (iv) the Charpyimpact strength of the polycarbonate resin composition is higher thanthe Charpy impact strength of the polycarbonate resin (a), and (v) theCharpy impact strength of the polycarbonate resin composition is atleast 8 kJ/m², wherein the Charpy impact strength is measured accordingto JIS K7111 on a molded specimen having a notch of 0.25 mmR, whereinthe polycarbonate resin (a) is a polycarbonate resin having structuralunits derived from a compound represented by the following formula (1a):


2. A polycarbonate resin composition comprising at least a polycarbonateresin (a) and a polycarbonate resin (b) having structural unitsdifferent from the polycarbonate resin (a), wherein the polycarbonateresin (b) has bis-phenol A structural units, which satisfies thefollowing requirements: (i) the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is higher than the pencil hardnessof the polycarbonate resin (b) as specified by ISO 15184; (ii) theweight ratio of the polycarbonate resin (a) to the polycarbonate resin(b) is from 10:90 to 30:70; (iii) the ratio of the viscosity averagemolecular weight Mv(a) of the polycarbonate resin (a) to the viscosityaverage molecular weight Mv(b) of the polycarbonate resin (b),Mv(a)/Mv(b), is at least 0.02 and at most 1.5, and (iv) the Charpyimpact strength of the polycarbonate resin composition is at least 8kJ/m², wherein the Charpy impact strength is measured according to JISK7111 on a molded specimen having a notch of 0.25 mmR, wherein thepolycarbonate resin (a) is a polycarbonate resin having structural unitsderived from a compound represented by the following formula (1a):


3. The polycarbonate resin composition according to claim 2, wherein theabove Mv(a) is at most 20,000.
 4. A polycarbonate resin compositioncomprising at least a polycarbonate resin (a) and a polycarbonate resin(b) having structural units different from the polycarbonate resin (a),wherein the polycarbonate resin (b) has bis-phenol A structural units,which satisfies the following requirements: (i) the pencil hardness ofthe polycarbonate resin (a) as specified by ISO 15184 is higher than thepencil hardness of the polycarbonate resin (b) as specified by ISO15184; (ii) wherein the weight ratio of the polycarbonate resin (a) tothe polycarbonate resin (b) is from 10:90 to 30:70; (iii) the meltviscosity of the polycarbonate resin (b) at a temperature of 280° C. ata shear rate of 122 sec⁻¹ is higher than the melt viscosity of thepolycarbonate resin (a) at a temperature of 280° C. at a shear rate of122 sec⁻¹, and (iv) the Charpy impact strength of the polycarbonateresin composition is at least 8 kJ/m², wherein the Charpy impactstrength is measured according to JIS K7111 on a molded specimen havinga notch of 0.25 mmR, wherein the polycarbonate resin (a) is apolycarbonate resin having structural units derived from a compoundrepresented by the following formula (1a):


5. The polycarbonate resin composition according to claim 1, wherein thepencil hardness of the polycarbonate resin (a) as specified by ISO 15184is at least F.
 6. The polycarbonate resin composition according to claim1, wherein the pencil hardness of the polycarbonate resin composition asspecified by ISO 15184 is at least HB.
 7. The polycarbonate resincomposition according to claim 1, which has a yellowness index (YI) ofat most 4.0.
 8. The polycarbonate resin composition according to claim1, which further contains a flame retardant.
 9. A method for producingthe polycarbonate resin composition as defined in claim 1, whichcomprises melt-kneading the polycarbonate resin (a) and thepolycarbonate resin (b).
 10. A method for producing the polycarbonateresin composition as defined in claim 1, which comprises dry-blendingthe polycarbonate resin (a) and the polycarbonate resin (b).
 11. Aninjection-molded article, which is obtained by injection-molding thepolycarbonate resin composition as defined in claim
 1. 12. An extrudedarticle, which is obtained by extruding the polycarbonate resincomposition as defined in claim
 1. 13. The extruded article according toclaim 12, which is a sheet or a film.
 14. A molded article ofpolycarbonate resin having structural units (a) derived from a compoundrepresented by the following formula (1a) and structural units (b)different from the structural units (a), wherein the structural units(b) are bis-phenol A units and wherein the weight ratio of thestructural units (a) to the structural units (b) is from 10:90 to 30:70based on the total weight of the structural units (a) and the structuralunits (b), wherein the ratio of the content [S] of the structural units(a) on the surface of the molded article of polycarbonate resin to thecontent [T] in the entire molded article of polycarbonate resin([S]/[T]) is higher than 1.00 and at most 2.00:


15. The molded article of polycarbonate resin according to claim 14,which is an injection-molded article.
 16. The molded article ofpolycarbonate resin according to claim 14, wherein the ratio of thecontent [S] of the structural units (a) on the surface of the moldedarticle of polycarbonate resin to the content [T] in the entire moldedarticle of polycarbonate resin ([S]/[T]) is at least 1.01 and at most1.50.
 17. The molded article of polycarbonate resin according to claim14, wherein the pencil hardness on the surface of the molded article ofpolycarbonate resin as specified by ISO 15184 is at least HB.
 18. Themolded article of polycarbonate resin according to claim 14, whichcomprises at least a polycarbonate resin (a) having structural units (a)derived from the compound represented by the formula (1a) and thepolycarbonate resin (b) having bis-phenol A structural units.
 19. Themolded article of polycarbonate resin according to claim 18, wherein thepencil hardness of the polycarbonate resin (a) as specified by ISO 15184is higher than the pencil hardness of the polycarbonate resin (b) asspecified by ISO
 15184. 20. The molded article of polycarbonate resinaccording to claim 18, wherein the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is at least F.
 21. The moldedarticle of polycarbonate resin according to claim 18, wherein theviscosity average molecular weight of the polycarbonate resin (a) ishigher than the viscosity average molecular weight of the polycarbonateresin (b).
 22. A method for producing the molded article ofpolycarbonate resin as defined in claim 18, which comprisesmelt-kneading or dry-blending the polycarbonate resin (a) and thepolycarbonate resin (b), followed by molding, wherein the viscosityaverage molecular weight of the polycarbonate resin (a) is higher thanthe viscosity average molecular weight of the polycarbonate resin (b).23. The method for producing the molded article of polycarbonate resinaccording to claim 22, wherein the molding is injection molding.
 24. Thepolycarbonate resin composition of claim 1, wherein at least 50 wt %based on 100 wt % of all the structural units in the polycarbonate resin(a) are of formula (1a) wherein the polycarbonate resin (b) is apolycarbonate resin having mainly bis-phenol A structural units (b). 25.The polycarbonate resin composition of claim 2, wherein at least 50 wt %based on 100 wt % of all the structural units in the polycarbonate resin(a) are of formula (1a), and wherein the polycarbonate resin (b) is apolycarbonate resin having mainly bis-pehnol A structural units (b). 26.The polycarbonate resin composition of claim 4, wherein at least 50 wt %based on 100 wt % of all the structural units in the polycarbonate resin(a) are of formula (1a) wherein the polycarbonate resin (b) is apolycarbonate resin having mainly bis-pehnol A structural units (b). 27.The polycarbonate resin composition of claim 1, wherein thepolycarbonate resin (a) is a homopolymer of structural units derivedfrom the compound of formula (1a).
 28. The polycarbonate resincomposition of claim 2, wherein the polycarbonate resin (a) is ahomopolymer of structural units derived from the compound of formula(1a).
 29. The polycarbonate resin composition of claim 4, wherein thepolycarbonate resin (a) is a homopolymer of structural units derivedfrom the compound of formula (1a).
 30. The molded article ofpolycarbonate resin claim 18, wherein the polycarbonate resin (a) is ahomopolymer of structural units derived from the compound of formula(1a).
 31. The polycarbonate resin composition according to claim 1,having a Charpy impact strength of at least 10 kJ/m².
 32. Thepolycarbonate resin composition according to claim 2, having a Charpyimpact strength of at least 10 kJ/m².
 33. The polycarbonate resincomposition according to claim 4, having a Charpy impact strength of atleast 10 kJ/m².